The Jacobson Center for Writing, Teaching and Learning offers individual help with writing and also this useful guide:
Writing Papers: A Handbook for Students at Smith College
Read "When to Cite" starting on page 52 (pg. 60 of 80 in pdf file).
The University of Washington's School of International Studies Writing Center has a concise guide for writing a Political Science proposal (including a literature review): How to Write Research Proposals
The CSU San Marcos library has a political science research guide which includes advice and tools to use: Literature Review