1) About which 2) From which 3) Of which 
of what
• (adv.) Of which; of whom; formerly, also, with which; -- used relatively. • (adv.) Of what; -- used interrogatively.
Where·of' adverb 1. Of which; of whom; formerly, also, with which; - - used relatively. « I do not find the certain numbers whereof their armies did consist.» Sir J. Davies. « Let it work like Borgias' wine, Whereof his sire, the pope, was poisoned.&...
[adv] - of which 2. [adv] - of what