The Chicago Manual of Style Online is used in the MDiv and MAR programs. Guide to style, usage, and grammar.
Turabian is a subset of the style guide. Chicago Manual of Style will cover everything from Turabian.
APA Style and Grammar Guidelines--From the American Psychological Association website, "The style and grammar guidelines pages present information about APA Style as described in the Publication Manual of the American Psychological Association, Seventh Edition."
APA Citation Information from the Online Writing Lab at Purdue University. This covers all the important aspects of writing and citing from the current APA Style Guide.