Referencing is an important part of academic writing because it shows where you got your information from. When you use someone else’s work or ideas, you have to acknowledge their effort by placing a reference in the text and in the reference list at the end. If you do not, you may be accused of plagiarism. The system you use in each case will be different but you must always use the same one: that is to say, you must use the same referencing style.

There are many different referencing styles, but the most common styles in the natural sciences are Chicago , Harvard (whose style is explained online by a number of different institutions, including the Open University’s Library Services ) and the Publication Manual of the American Psychological Association(APA) . Such guides stipulate the information you must include, the order it must be in and how it must be punctuated. They also stipulate the differences between referencing in the text and in the reference list, and how to reference different text types.

In the APA style for in-text references, for example, you must include the name of the author or authors and the year of publication, and you may decide to include the page number. The in-text reference itself may be a paraphrase or a quotation.



The APA style for referencing a work in the list of references at the end of the text depends on whether the work is a book or journal article. In the case of a book, the style is as follows: Author, A. (Year of publication). Title of book. Publisher.


In the case of an article, the style is as follows: Author, A.A., Author, B.B., & Author, C.C. (Year of publication). Title of article. Title of journal, volume, issue, pages.

 
There are many good self-help websites on how to correctly reference your sources following APA guidelines. One such is published by the Purdue Online Writing Lab website , which also offers help on other citation systems.