Some Points :
1. Commerce & Accountancy (Comm.) Is a blend of Numerical + Theoretical Papers.
2. Don’t go for bulky books as stated in quora like K. Ashwthappa for HRM , CB Gupta for OB, Aruna Jha for Audit, Khan for FM, ML Agarwal for Costing, PC Tulsian for Accounts.
3. These are University Books and even in University nowdays small volume books in the form of guide are adopted for ease.
4. Don’t depend on Rankers material completely you must supplement it with some small books like Vishal Guide for HRM IR OT. The book that are in the Q & A are the best.
Book list (Rankers Materials are must plus you may be buy the following books )
Accounts : CA Inter Materials
Audit: Pankaj Garg Book / Aruna Jha
Costing : Pearson Book
Tax : Vinod Singhania / TN Manoharan
FM : Only CA Materials
Financial Institutions: Ramesh Singh GS Book
OT OB : VSP Rao
HRM : LM Prasad
IR : Mostly Part covered in HRM so no seperate Book.