This is the bible(though a bit old) for most SAP FI/CO---David Nowak and Quinten Hurst
Question and Answers by Narayanan.
New GL by Eric Bauer...This is a useful book and must be read sideby side with Hurst.
For Migration issues--Paul Theobald.
Financial reporting by Aylin Korkmaz
Key components reviewed well by Manish Patel.
Naeem Arif's new book