Christian Copyright Licensing International – For music lyric permissions
Copyright Clearance Center – Register your for work for use by others or to obtain permission
How to Cite Material Obtained from the Internet – Chicago Manual of Style (This is the style guide all book publishers use.)
Buy the book, The Copyright Handbook: How to Protect and Use Written Works 13th Edition by Stephen Fishman, Nolo Press (2017).
Buy the book Getting Permission: How to License & Clear Copyrighted Materials Online & Off – Richard Stim, Nolo Press (2016).
Buy the book, The Copyright Permission and Libel Handbook : A Step-By-Step Guide for Writers, Editors, and Publishers(Wiley Books for Writers) by by Lloyd J. Jassin and Steve C. Schecter, John Wiley & Sons Publishing. – Published in 1998 but still a fine resource.