I remember seeing that first when I was in my teens and thought while it was true naturism, there was something odd about it. IE: 'where are the guys..".
Still, the subjects were definately naturist and definately from this link on Amazon, real and into it.
Holy Nature: A Celebration of Naturism in Today's Russia
This well written book presents a group of people, in St. Petersburg (former Leningrad), Russia, who call themselves 'The Free Body Culture Society'. Filled with large color photographs of the men, women and children who make up this 'Society', this book brings the unique group to life for the reader. Concerned with the health of their environment, the Free Body Culture Society Members are also the founders of the Russian Green Party. They spend their social time enjoying ancient 'Rus' festivals, sunny days at the beach and Russia's famous 'white nights' around the bonfire. Some events photographed in this book include: 3 females in the country, Children's Day at the beach, Ivana Kupala (The Night of Love), and a Naturist Wedding. As well, their are interviews of the photographer, Mikhail Rusinov, and child naturist, Alla.
http://www.amazon.com/exec/obidos/ASIN/0966460901/findcroatia-20