Citing the work that supports your research is both an ethical issue and a legal issue.
The ethics of citing is based on the scholarly tradition of giving credit for information and ideas that are not one's own. Science has a long tradition of acknowledging priority through citations. You have the ethical responsibility to cite all works that were used to support your research, to give credit to the earlier work and to provide a clear path for those who follow in your footsteps.
As so eloquently expressed by Isaac Newton in a letter to Robert Hooke in 1675,1
If I have seen further it is by standing on ye sholders of Giants.
The legal issues of citing one's sources are codified in Copyrights, Title 17 of the U.S. Code, which describes the legal protections of authors' and creators' intellectual property rights.
1. Merton RK. On the shoulders of giants: a Shandean postscript. New York: The Free Press, 2006. p. 31.
Plagiarism is defined as:
"The action or practice of taking someone else's work, idea, etc., and passing it off as one's own; literary theft."
Oxford English dictionary [Internet]. 3rd ed.; online version. [Oxford]: Oxford University Press, 2006. Plagiarism;[cited 2011 Oct 11]:[about 2 screens]. Available from: http://oed.com
The Vancouver style is also known as the Uniform Requirements for Manuscripts Submitted to Biomedical Journals. The Uniform Requirements for Manuscripts refers authors to NLM's Citing Medicine to get more information and examples on recommended formats for various reference types.
Example citations based on rules from: Patrias K. Citing medicine: the NLM style guide for authors, editors, and publishers [Internet]. 2nd ed. Wendling D, technical editor. Bethesda (MD): National Library of Medicine (US); 2007- [updated 2011 Sep 15; cited 2011 Oct 11]. Available from: http://www.nlm.nih.gov/citingmedicine
Citing a Journal Article
Bell KP, Phillips C, Paquette DW, Offenbacher S, Wilder RS. Incorporating oral-systemic evidence into patient care: practice behaviors and barriers of North Carolina dental hygienists. J Dent Hyg. 2011 Spring;85(2):99-113.
Citing a Journal Article on the Internet
Rodda J, Walker Z, Carter J. Depression in older adults. BMJ [Internet]. 2011 Sep 28[cited 2012 Sep 12];383:d5219. Available from: http://www.bmj.com/content/343/bmj.d5219.full DOI: 10.1136/bmj.d5219
Mason J. Concepts in dental public health. Philadelphia: Lippincott Williams & Wilkins; c2005.
Citing a Chapter in a Book
Palleschi KM. Dental hygiene care plan and evaluation. In: Darby ML, Walsh MM, editors. Dental hygiene: theory and practice. 3rd ed. St. Louis: Saunders/Elsevier; 2010. p. 372-99.
Zotero, a FireFox plugin, is a useful tool to help you manage your citations
Endnote Basic is an application that imports citations from your searches in web databases and helps you organize your references. It works with Microsoft Word helping you create in-text citations, footnotes, and bibliographies. See the EndNote Basic Guide for more information. A paid version of Endnote is available as well. See the EndNote Guide for more information.