Thank you for the information! Most likely you are right.
Look at this magazine, page 13. There is bilingual article about Anker-Record. Unfortunately, it has a lot of emotions and a few facts. However, the article makes it clear that its author Philipp Kroll can not be Anker-Record recording engineer as it is stated in the P.N.Grünberg book.
There is another mistake in Grünberg book - the Anker-Record records appeared on Russian market much earlier than 1910. The first mentioning I found in the The Gramophone News magazine, ¹1, April 1907, page 20 where it said that the price of Anker-Record records is 1 Ruble 75 kopeks for single-sided grand, 2 Rubles 50 kopeks for double-sided grand.