I was not able to find the origin of the name *Petrov* in the Petrov-Galerkin method for the numerical approximation of PDEs. 

Wikipedia refers to a certain Alexander G. Petrov, but it is still not clear who he was: on the Internet I found two persons called Alexander G. Petrov, both born during the 40's, but I think that the Petrov I am looking for should be born before, since Boris Galerkin lived in 1871-1945.

Can you suggest me any bibliographic resource to consult?