Finding scientific information

Number of authors

APA guide: Author–Date Citation System

Number of authors to include in an in-text citation:

See also:

Citing Authors With the Same Surname

Paraphrasing

APA guide: Paraphrases
APA guide: Parenthetical Versus Narrative In-Text Citations

When paraphrasing (indirect quotations), a single sentence is cited either:

• at the end of the sentence (parenthetical citation): 
  Xxxxxxxx xxxxxxx xxxxxx (Smith, 2025, p. 123). 
  or
• within the sentence (narrative citation), in which case the page number is added at the end of the sentence before the period: 
  According to Smith (2025)... (p. 123).

If the citation applies to multiple sentences, it is sufficient to mention the author's name in the first sentence (narrative citation), as long as it is clear from the following sentences in the same paragraph that the same source is being used. A possible page number is added in parentheses at the end of the citation.

Smith (2025) describes... According to him... Smith also highlights... It can therefore be stated that... (pp. 11–14).

APA guide: Citing Multiple Works

If you refer to multiple sources within the same paragraph, list them in alphabetical order within parentheses and separate the sources with a semicolon (;). If you are citing multiple works by the same author, place the oldest source first.

(Smith, 2025; Johnson, 2023; Williams, 2024)

(Smith, 2020; Smith, 2025)

Direct quatations

APA guide: Quotations

When making a short direct quote (under 40 words), it is placed within the sentence using quotation marks.

Xxxxxxxx xxxxxxx xxxxxx "short direct quote" (Smith, 2025, p. 123). 

When making a long direct quotation (at least 40 words), it is indented without quotation marks and formatted with increased line spacing.

Xxxxxxxx xxxxxxx xxxxxx:

Long direct quotation. Long direct quotation. Long direct quotation. Long direct quotation. Long direct quotation. Long direct quotation. Long direct quotation. Long direct quotation. (Smith, 2025, p. 123)

Page numbers

APA guide: Paraphrases

If you are referring broadly to an entire work or study, a page number is generally not included. However, APA recommends adding a page number if it helps the reader locate the relevant part of the source, such as in a book.

APA guide: Citing Specific Parts of a Source

Include page numbers when:

• referring to an image, table, or other detailed information, 
• using a direct quotation.

(Smith, 2025, pp. 11–14)

Use an en dash (–) between page ranges. Computer editing tip
 

APA guide: Direct Quotations of Material Without Page Numbers

If the source has no page numbers (e.g., a page-free e-book), refer to the chapter or subsection instead.

(Smith, 2025, para. 3)
(Smith, 2025, section 5.3, para. 6)

Secondary Source

APA guide: Secondary Sources

If possible, use the original source — that is, the publication in which the information was first reported.

A secondary source is acceptable if the original source is impossible to obtain or is written in a language you do not understand. Include only the source you actually used in the reference list. Also, mention the original source in the in-text citation.

In-text citation: (Smith, 1982, as cited in Williams, 2014)
Reference list: Williams, J. (2014). Title. Journal, 1(1), 1-11.

When you cite a book, the reference list should include the following bibliographic information:

• Name of author or editor
  • editor's name is followed by (ed.) or corresponding abbreviation
  • organizational authors' names are given in the same form as they appear in the publication, with the main organization listed first and the suborganization after that
  • if there is no personal or organizational author, the reference starts with the title of the publication
• Year of publication. When no year of publication is indicated, use the copyright year or (n.d.), meaning "no date".
• Title of the publication in italics
• Edition information is always included, when the publication is other than first edition
  • include any edition information in parentheses after the title, without italics in the form it appears in the publication
• Publication series, if the publication has been published in a series, e.g. Peltola, M., Keskitalo, P., Äärelä, R., & Aikio, A. (2019). Saamelainen varhaiskasvatus nyt: Arvot, käytänteet ja osallisuus arjessa. (Acta Universitatis Ouluensis. F, Scripta academica nro 13). Oulun yliopisto.
• Publisher

Bennett, D. (2005). The art of precast concrete: Colour, texture, expression. Birkhäuser. https://doi.org/10.1007/3-7643-7668-6
Ympäristöministeriö. (2016). Eläköön lähiö! : 22 reseptiä lähiöelämään. Ympäristöministeriö.

Author, A. A. (2020). Title of work (2nd ed.). Publisher.
Author, A. A. (2020). Title of work. Publisher. http://www.xxxxxx
Author, A. A. (2020). Title of work. https://doi.org/xxxxx
Editor, A. A. (Ed.). (2020). Title of work. Publisher.

How to add a chapter from an edited book to Mendeley?

• Use the book section citation type. Use the title and author of the chapter as the section title. Include the author(s), editors and book title, as well.

Author, A. A., & Author, B. B. (2017). Title of article. In A. Editor, B. Editor, & C. Editor (Eds.), Title of the book (pp. 1–111). Publisher.

Merchant, G. (2017). Hands, Fingers and iPads. In C. Burnett, G. Merchant, A. Simpson, & M. Walsh (Eds.), The Case of the iPad: Mobile literacies in education (pp. 245–256). Springer.

Include any edition information in the same parentheses as the page range of the chapter, separated with a comma. E.g.:

 Dillard, J. P. (2020). Currents in the study of persuasion. In M. B. Oliver, A. A. Raney, & J. Bryant (Eds.), Media effects: Advances in theory and research (4th ed., pp. 115–129). Routledge.

There is slight variation in the way articles in journals and edited books are entered.

Conference presentations are often published in books or periodicals. If there are no conference proceedings, include the authors, full dates of the conference, the title of the presentation [describe the presentation in square brackets after the title] followed by the name and place of the conference (instructions).

   Conference proceeding:

Fahrenberg, U., Jipsen, P., & Winter, M. (Eds.). (2020). Lecture notes in computer science: Vol. 12062. Relational and Algebraic Methods in Computer Science: 18th International Conference, RAMiCS 2020, Palaiseau, France, April 8–11, 2020, Proceedings. Springer Nature. https://doi.org/10.1007/978-3-642-21070-9

As a book chapter:

Katz, I., Gabayan, K., & Aghajan, H. (2007). A multi-touch surface using multiple cameras. In J. Blanc-Talon, W. Philips, D. Popescu, & P. Scheunders (Eds.), Lecture notes in Computer Science: Vol 4678. Advanced concepts for Intelligent Vision Systems (s. 97–108). Springer. https://doi.org/10.1007/978-3-540-74607-2_9

In a journal:

Rönkkö, T., Kuuluvainen, H., Karjalainen, P., Keskinen, J., Saukko, E., Järvinen, A., Silvennoinen, H., Rostedt, A., Olin, M., Yli-Ojanperä, J., Dal Maso, M., Hillamo, R., Timonen, H. J., Saarikoski, S., Niemi, J. V., Kousa, A., Pirjola, L., & Nousiainen, P. (2017). Traffic is a major source of atmospheric nanocluster aerosol. Proceedings of the National Academy of Sciences of the United States of America, 114(29), 7549–7554. https://doi.org/10.1073/pnas.1700830114

Conference presentation:

Viitanen, K., & Reiman, T. (26–29 June 2017). Building an adaptive safety culture in a nuclear construction project - insights to safety practitioners [Conference presentation]. 7th Resilience Engineering International Symposium, Liège, Belgium. http://www.resilience-engineering-association.org/resources/symposium-papers/2017-liege-luik-b/

Include author, time of publication, title and publication channel. 

Published dissertations and theses

Tiiro, A. (2018). Effect of visual realism on cybersickness in virtual reality [Master's thesis, University of Oulu]. OuluREPO University of Oulu Repository. http://urn.fi/URN:NBN:fi:oulu-201802091218

Oikarinen, E. (2018). Perspectives on humor in recruitment advertising on the Internet (Acta Universitatis Ouluensis. G, Oeconomica 97) [Doctoral dissertation, University of Oulu]. OuluREPO University of Oulu Repository. http://urn.fi/urn:isbn:9789526218397

Unpublished dissertations and theses

Author, A. A. (year). Title [Unpublished doctoral dissertation/Unpublished master's thesis]. Name of Institution.

For patents, include the names of the inventor(s), effective year, country and patent number. In text, cite the patent number, not the names of the inventors, e.g. (Finnish patent FI20000522, 2001)

Kinnunen, H., & Nissilä, S. (2001). Finnish patent FI20000522. Finnish patent and registration office.

Kinnunen, H., & Nissilä, S. (2001). U.S. Patent US2001023320. https://fi.espacenet.com/publicationDetails/biblio?FT=D&date=20010920&DB=&locale=fi_FI&CC=US&NR=2001023320A1&KC=A1&ND=4

For standards, include the standardizing organization and year, as well as the title and identifier of the standard. An example of an in-text citation: 

International Organization for Standardization. (2016). Occupational health and safety management systems—Requirements with guidance for use (ISO/DIS Standard No. 45001). http://www.iso.org/iso/catalogue_detail?csnumber=6378 

For maps, include the title of the map and possible map series; if the cartographer's name is given, enter it as the author. If there are user-defined locations in online maps, enter them in square brackets.

Google. (n.d.). [Google Maps directions for driving from Ingolstadt, Germany, to Geneva, Switzerland]. Retrieved August 4, 2015, from 
https://goo.gl/maps/ILt8O

Karttakeskus. (2014). Hevonkack ja muita alatyylisiä paikannimiä Suomesta [Map]. Karttakeskus.

In text

When citing an act, use its official abbreviation (you have to specify the act when it appears for the first time in your text), chapter, section and subsection. Example (KPL 3:9.2 §)

You can check the correct spelling of abbreviations of acts and decrees in the Finlex and Edilex databases, or in the printed books Suomen Laki or Suomen säädöskokoelma. For example on https://www.edilex.fi/#toolbar=tab-abbreviations

In reference list

Kirjanpitolaki 30.12.1997/1336.

____________

The APA style has been applied in this example.

When you cite electronic sources, you must indicate how to access them. You may leave links active.

• Use a permanent link if possible, for example DOI, URN, Handle or so-called permalink. Create a link from a DOI as follows: https://doi.org/[DOI identifier.] Use the Crossref service to find out the DOI of a publication.
• Reference to a source in an online archive, for example Internet Archive or Memento, either an existing one or one uploaded by you.
• URL address

Aivelo, T. (2020, April 20). Koronavirus leviää superherkästi [Blog post]. Kaiken takana on loinen. https://www.tiede.fi/blogit/kaiken-takana-loinen/koronavirus-superleviaa-herkasti
 

Hakala, J. (2017). E-viittaamisen ihanuus ja kurjuus. Informaatiotutkimus, 36(2), pp. 77–85. https://doi.org/10.23978/inf.65190

Bank of Finland. (n.d.). Exchange rates. Retrieved April 27, 2021 from  https://www.suomenpankki.fi/en/Statistics/exchange-rates/ 

• when pages change over time but are not archived, include a retrieval date in the reference.

OpenAI. (2023). ChatGPT (Mar 14 version) [Large language model]. https://chat.openai.com/chat

• see How to cite ChatGPT

Reference examples

Reference list setup

Entries starting with "a", "and", "the"

If you are citing more than 20 authors: after the 19th author's name, use an ellipsis in place of the author names, then add the final author name. There are no more then 20 names.

References

Aliev, M. R., & Watson, J. (1985). Higher-order effects in the vibration-rotation spectra of semirigid molecules. In K. N. Rao (Ed.), Molecular spectroscopy: Modern research (pp. 1–67). Orlando: Academic Press.

HART Communication Foundation. (2009, December 22). Wireless hart. Retrieved from http://www.hartcomm.org/

McDuff, C., Smith, J., Kensington, K., Jones, S., Coughlan, S., Bortolin, L., Witte, M., Scott, A., Newport, A., Jensen, K., Wutzler, J., van Staden, I., McLean, J., Bergsma, G., Dowman, B., Petrie, K., Higgens, D., McCloud, R., Jessop, L., . . . Duncan, P. (2017). An introduction to quantitative analysis in finance. Houghton.

Mitra, S. K. (1991). Some unconventional signal processing applications of multirate techniques. Proceedings - IEEE International Symposium on Circuits and Systems 1, 13–16.

Paulson, M. (1992). Basement membrane proteins: Structure, assembly, and cellular interactions. Critical Reviews in Biochemistry and Molecular Biology, 27(1–2), 93–127. https://doi.org/10.3109/10409239209082560

Paulsson, M., Saladin, K., & Landwehr, R. (1988). Binding of Ca2+ influences susceptibility of laminin to proteolytic digestion and interactions between domain-specific laminin fragments. European Journal of Biochemistry, 177(3), 477–481. https://doi.org/10.1111/j.1432-1033.1988.tb14396.x

Royal Mardsen Hospital Bone-Marrow Transplantation Team. (1977). Failure of syngeneic bone-marrow graft without preconditioning in post-hepatitis marrow aplasia. Lancet, 310(8041), 742–744. https://doi.org/10.1016/S0140-6736(77)90241-0

Watson, M. A. J. (1985). Higher-order effects in the vibration-rotation spectra of semirigid molecules. Molecular Spectroscopy: Modern Research, 3, 1.

Zar, J. H. (1984). Biostatistical Analysis. Prentice-Hall.