Purdue's OWL (Online Writing Lab) APA Guide
Knightcite is an online citation generator service provided by the Hekman Library of Calvin College; it's free but you register to use it.
Purdue's OWL (Online Writing Lab) Chicago Guide
Society of Biblical Literature (citing sacred text)
Purdue's OWL (Online Writing Lab) MLA Guide
MLA Formats for music (songs, recordings, compositions, etc.) (Courtright Memorial Library, Ottbein University)