The main sources used in science are reseach articles and review articles published in peer-reviewed academic journals. Other common source types are books and chapters from edited books and websites are also sometimes used. As a general rule, you can say that within science it is still more acknowledged to use the more traditional sources, i.e. research articles, review articles, books and chapters in books than websites.
Since library databases include citations to all sorts of sources it's important to be able to identify different types.
A research article (or original article or research paper) is an article published in an academic journal where researchers publish the results of their original, empirical research and it is a primary source. A very important part of the research article publishing process is peer reviewing. Peer reviewing is a process that academic journals use to ensure the articles they publish are of high quality. When an article is submitted to a peer reviewed journal, the editors send it out to other researchers in the same field (the author's peers) to get their opinion on the quality of the work, its relevance to the field, its appropriateness for the journal, etc.
Abstract: A brief, comprehensive summary of the article, written by the author(s) of the article.
Introduction: This introduces the problem, tells you why it’s important, and outlines the background, purpose, and hypotheses the authors are trying to test.
Material & Methods: Describes in detail how and, if a field study, where the research was conducted, and may be subdivided into subsections describing design of experiment, apparatus used and statistical methods.
Results: Summarize, analyze and present the data. It should be sufficiently detailed to justify the conclusions.
Discussion: The authors explain how the data fits their original hypothesis, compare with other results, state their conclusions, and look at the theoretical and practical implications of their research.
References: A list of all sources cited in the article.
A review article is an attempt by one or more scientists to sum up and analyze the current state of the research on a particular topic. Since a review article sums up results published in primary research articles it is a secondary source. Ideally, the author(s) searches for everything relevant to the topic, and then sorts it all out into a coherent view of the “state of the art” as it now stands. Review articles give you information on the background and context of a subject as well as the main people working in a field, recent major advances and discoveries, significant gaps in the research, current debates and ideas of where research might go next.
Review articles are virtual gold mines if you want to find out what the key articles are for a given topic. If you read and thoroughly digest a good review article, you should be able to “talk the talk” about a given topic. Unlike research articles, review articles are good places to get a basic idea about a topic.
There are different types of review articles:
There are different types of books:
Textbooks offer a broad-based foundation to the study of subject. There are also more advanced textbooks, but still textbooks contain well established knowledge and the latest findings are (usually) not included.
Specialist topic books deals with more narrow topics in a more scientific way. Specialist topic books are often edited i.e. the different chapters in the book are written by different authors who are experts at their part of the topic respectively. In edited books it is the chapter that is the entity you are using as a source and what you are going to write a reference to. Since writing a reference to a chapter from an edited book differs from writing a reference to a full book you will find specific instructions on how to write a correct reference to a chapter from an edited book in the section about "How to write...".
Reports are written documents which present focused, salient content, generally to a specific audience. Reports are often published by different governmental bodies, i.e. Environmental Protection Agencies, but it is also common within business, education, science, and other fields, and are often to display the result of an experiment, investigation, or inquiry. Reports are not at all as strictly defined as a research article.
A website is a page or collection of pages on the World Wide Web that contains specific information which was all provided by one person or entity and traces
back to a common Uniform Resource Locator (URL).
In contrast to research articles there is NO peer reviewing process for webpages/websites!!! Anyone can publish anything on the web. So be careful! You should be very critical and try to find out as much as you can about the authors of a website before you use it as a source. There are lots of information on how to evaluate the quality of a website, see links below. A quick start is to take a look at the letters after the dot in the link:
.edu which denotes education
.ac denotes academic
.org denotes organisation
.gov denotes government
.com denotes commercial
.soc denotes society
You should provide an in-text citation for any images, illustrations, photographs, diagrams, tables or figures that you reproduce in your work, and provide a full reference as with any other type of source you use. When you use an image or a picture you did not create yourself, you must provide a citation and most often you have to get permission from the copyright holder to use the image.
When you have got information by talking with a person you should address this as personal communication. Personal communication is denoted pers. comm. in the text.
In the reference list you should add the name of the person and telephone number and/or e-mail address to make it possible for other persons to contact your source.