Different disciplines adopt different citation styles. Be sure you know the citation style for your chosen discipline and specific assignment. If in doubt, check with your instructor.
Always check with your instructor for his or her preferred format.
Council of Science Editors SMC, editor. Scientific style and format: The CSE manual for authors, editors, and publishers. 7th ed. Reston, VA: The Council; 2006. (print only, find in a library near you)
The CSE number style has been revised and is now consistent with AMA.
Turabian is "essentially the same [style as] The Chicago Manual of Style, 15th edition, with slight modifications for the needs of student writers."