Researching a world theatre tradition

For the last 12 years I have been researching Kathakali, and as time goes on I see more and more ways to find out about the history of a tradition. Also, as time goes on I come across more and more conflicting pieces of information. It is therefore essential to cross reference all your information, find a range of sources to refer to and also check, double check and triple check you understand what you are reading before you choose ...