Most likely You have a job Platonova Alekseya G. ( 1877-?) his brother Platunov Michael G. (E.)(1887-1972), known artist and teacher.
Here the price of the work of Alexei Platonov ,
http://auction-ruseasons.ru/documents/rs_sait4.pdf , lot 67 , or here
http://rusant.ru/sample-category--p-594.html , I think somehow will help You soryentyrovatsya.
Good luck!
Sincerely,