Hi, this is clearly my point of view and is totally subjective, the best material for ISCA is the study material however there is just one problem is Remembering what you have read. To check this just do one thing If you have read at least twice any chapter from the study material and can reciprocate atleast all the headings of each topic/question and atleast one line explaining each heading. But if you couldn’t then go for an additional book by Sunil sethi sir or Swapnil Patni sir or Manish velecha sir,
For choosing which book suits you best go through each of the books and analyse the language and mnemonics.
if you can prepare concise notes from study material, it will help you both ways... helps learning thoroughly and enables quick revision... it is suggested to read isca every day if you do not have real interest in isca but just for the sake of course only... this technique will surely help and seal the security issues related to this subject...this is tried, tested and proved one... dont take chance with any subject, particularly isca...