costing syllabus is vast. practice manual of ICAI is very important. so one book which covers PM questions ,+ past questions+RTP questions is PADHUKA PUBLICATIONS BOOK.
it covers concept + practical + theory questions.
but keep in mind whatever book you choose, don't forget to study practice manual.
Dost padhuka me que karne ka tarika unique h... Practice mat me b ans ko khicha hua h but padhuka me wo short h but aisa nh kam h pura h jo wxam me help karega... Mene khudne self study ki h n padhuka padi h.... Bht mehnat lagegi but uske alawa mene practice mat b nh kiya koi jarurt hi nh padi..... N tumko practice mat k 70 percent que padhuka me hi mil jayenge.... To best h karlo