the act or process of deceiving or misleading, especially by concealing the truth
  the use of false representations to gain an unjust advantage
  the act or instance of taking and using the thoughts, writings, inventions, etc., of another person as one's own

  it enables your tutor to check the sources of your information.
  it protects you from charges of plagiarism
  both of the above

  in the reference list or bibliography at the end of your assignment
  within the text of your assignment
  at the bottom of the page as a footnote