What don't you have to cite?

• Common knowledge:
  Well-known information that your readers are already familiar with. For example, in a math paper you wouldn't need to cite a source for the Pythagorean Theorem (the equation relating the lengths of the sides in a right triangle).

  Other examples include chemical symbols (e.g. CO₂ for carbon) or scientific names of plants and animals.

• Widely known facts:

  The first manned moon landing occurred in 1969

  George Washington was the first president of the United States.

• Widely known ideas:

  Heisenberg is generally regarded as the father of quantum mechanics.

• Your own ideas!