Knowledgeable of/about
** “Knowledgeable of/about” is derived from “know of/about”.
** Examples and explanations
I know of tensor calculus (I have heard the name, but that is about all I know.)
I know about tensor calculus (I have learned this subject and can do the calculations.)
** References
http://english.stackexchange.com/questions/29869/know-about-vs-know-of