Group 1 –
SFM - J B Gupta book with DVD Lactures (BEST) (Taxmann Publication).
Group 2 –
AMA / Costing - Padhuka or Ravi M Kishore (BEST) plus Study Material, Compiler and Practice Manual (Prepare your own notes for theory portion – Must cover theory given in Practice Manual).
ISCA - Manish M Valechha ISCA TextBook (BEST) (Memory Based Edition)... it is Best book to secure high marks in ISCA. Very well written with awesome presentation… comprehensive yet easy to understand... It explains all topics with examples, diagrams, memory codes (refer Study Material if you have sufficient time but not actually required). And at last, go through Practice manual for important questions.
Direct Taxes - T.N. Manoharan Plus Summary Module of Vinod Gupta (Prepare notes for lengthy and typical portion, if possible). Also check T G Suresh’s DT book it is very concise book (BEST for revision). It can be completed easily.