When composing a work is crucial to cite everything that is not of your own authorship, through the use of citations and references list at the end of the work. The list of references should include all sources consulted and quoted throughout the work. Citations should be as complete as possible to allow the easily location of the item. You should also present the citations in a format / style appropriate.
There are several styles used on citing sources, in Portugal we use the Portuguese Standard is 405, but there are many others who can use.
Inform yourself about the existence and availability of bibliography management software that helps you not only to manage your personal collection of information, but also use some citation styles.
If in your research paper, you use parts of works of other authors and does’t reference them, readers will assume that everything is of your own authorship.This is plagianism and ir occurs when a work is presented with ideas or quotations from other authors without reference to them.
Remember that you will never be criticized for appeal and mention work of other researchers, in fact, doing it will gain credibility and strength in your research.