So, off down the online research rabbit hole I went!
First of all I keyed in 'book' and the place names in my search box without any luck. Then I keyed in the first listed character 'Tatyana Petrovna Vlasenkova', and bingo. Lots of Russian language sites and some English. I found out the book is 'Open Book'. I had seen the words 'Open Book' on the bookmark but did not at all twig that this was the name of the book! I thought that this was just a cute instruction to open the book!
Open Book was written by Veniamin Aleksandrovich Kaverin : "In 1949, Kaverin published the first installment of his trilogy Otkrytaya Kniga ("Open Book"), the last installment of which appeared in 1954. It is the story, spanning 35 years, of a woman microbiologist ('Tatyana Petrovna Vlasenkova') who proposes a bold new theory. The theory is opposed by the entrenched obscurantists, but the biologist presses on, at great personal expense. During the time he was working on this novel, Kaverin had to fight off critics who complained that he focused too much on love and who pressured him to part with his "not fully valuable" heroes and start occupying himself with ones absolutely positive in all respects."
Open Book is considered to be one of the great classics of Soviet literature and has been translated into English by Brian Pearce, among others. The story was turned into a feature film in 1973 and later it was turned into a nine-part television mini-series.
I ended up learning a lot from researching this 'boring' yet useful bookmark! One of the reasons I love collecting bookmarks.