I would like to give some explanation concerning my "official" versus "scientific" name ambiguity: KROUGLIK vs KRUGLIK.
In Russian language, my name is Сергей Геннадьевич КРУГЛИК, without any ambiguity.
During the perestroika, when Soviet scientists started to visit foreign countries, the name in the international passport had been translated according to French spelling by default, without any concertation with a person concerned. Thus, starting from 1992, the "official" name according to my first Soviet international passport was Serguei KROUGLIK; and it remains like this, from one passport to another ...
However, by that time I have already published several scientific papers at international conferences proceedings using English spelling of my name: Sergei G. KRUGLIK. Naturally I continue to use it for all my scientific publications.
Summarizing, when I need to use my passport or other official ID document, my "official" name is being used: Serguei KROUGLIK. And for communications within the scientific community and for the research articles I am using my "scientific" name: Sergei G. KRUGLIK.
"G" stands for the name of my father, Guennadi, who was a scientist himself working in theoretical physics.