Performing an information search starts with choosing a search strategy and familiarising oneself with the instructions and tools of the databases that are going to be used. When using a search string, the concepts of the subject matter should be described with alternative terms, parallel concepts and synonyms. Search terms with their truncation symbols and the operators connecting them form the search string, the presentation of which varies according the database. In the pearl growing strategy, the starting point is a relevant document which is used to find more literature on the subject. From the reference information in articles, more articles dealing with the same topic can be searched using the article that has already been found to be relevant. It is also possible to discover the interest an article has generated, and furthermore one can follow the development and impact of the research results and scientific theories.
In a search form, operators and search fields can be selected easily in the drop-down menus.
In this example, a search form from ProQuest ASFA database has been used to search for information about tsunami warning systems. As many synonyms/parallel expressions as possible have been used about both tsunamis and warning systems.
Image source: ASFA (ProQuest) <http://search.proquest.com> 30.7.2013.
There are often more search fields available in command search. Notice, that not all documents contain all fields. Searching specific fields may prevent some articles from appearing in your search results. In addition to codes selection Scopus Advanced search for example has SUBJTERMS(2216) field, where 2216 is ASJC-code (All Science Journal Classification) limiting the search into specific seubject area, in this case architecture. ASJC-codes can be found in Scopus Titlelist -exel on page http://www.info.sciverse.com/scopus/scopus-in-detail/facts.
Image source: Scopus <http://www.scopus.com> 22.8.2014
The command search allows the user to use the widest variety of ways for controlling a search; in a command search there is no need to be concerned about the limits that you have with forms, such as the number of search lines, and often there is a wider choice of search fields.
In this example, a search has been performed using the Web of Science command search on the same subject as the previous example. The search has been focused on Topic (TS) which searches in the following fields: Title, Abstracts, Author Keywords, Keywords Plus®.
The OR expression must be put in brackets to make sure that the search is performed in the right order.
Image source: Thomson Reuters - Web of Knowledge (Web of Science) <http://apps.webofknowledge.com> 23.7.2013
Sometimes a search can also be performed using natural language. The topic of the search can then be presented directly as a sentence, a question or a phrase which is then modified into a search string by the search engine. Some search engines only remove stop words (such as prepositions, the verb 'to be' etc.), but the more advanced search engines analyse the relationships of the terms statistically and grammatically. A search with natural language is particularly useful when starting a new search, but after the search, it is advisable to check how it has executed the search; this can be done, for example, by examining the search history.
In the SciFinder database, a search for a topic is performed directly with natural language. On the basis of a typed sentence, the search engine suggests different combinations of search terms, and it informs the user how many references it can find with each combination. Image source: SciFinder Scholar< http://scifinder.cas.org 10 July 2013