Start using a reference management tool from the beginning of your information retrieval for a seminar paper or a thesis or a research topic. Your references will stay in order and it will be easy to create a bibliography.
Mendeley is a free reference management application. Mendeley can be accessed both through the user interface installed on your computer and via the web.
You can find information about the functionality of the add-ins with different operating systems, browsers and word processing programs on the page What browsers and operating systems are supported for Mendeley products?