The prominent Russian scientists, Vladimir I. Vernadsky (1863–1945), whose 160-th anniversary we celebrate this year, and Nikolay A. (Nikolas) Rubakin (1862–1946), whose 160-th anniversary we celebrated last year, were both library workers and bibliographers. They both entered St. Petersburg Imperial University, the department for natural sciences of physics and mathemetics faculty, communicated closely when students, and maintained friends and scientific ties up to 1936. The cosmological and cosmographic ideas of Dmitry I. Mendeleev, their teacher, influenced them both. Like N. Rubakin, V. I. Vernadsky saw selfless service to the humankind as his supreme goal. In his studiesw of psychology, Rubakin came to the conclusion that human life passes at three levels, namely biological, social, and cosmical level. In his turn, Vladimir Vernadsky is among acknowledged adept of Russian cosmism and father of the teaching of noosphere. The humanitarian trend in Venradsky’s world outlook manifested as early in his life as did his interest in the natural sciences. He developed his strong humanist, social ethical ideals in his early years as the scientist and thinker. These two persons were both engaged in bibliographic work, synchronically for some period. Vladimir Vernadsky was among the founders of Moscow Commission for Home Reading of the Educational Department of the Society to Promote Technical Knowledge (1893); Nikolas Rubakin was a founder of the Department to Support Self-education at Petersburg Pedagogical Museum of Military Educational Institutions (1894). They both took the most active part in writing bibliographies of general and supplementary literature within the curricula of the two institutions. Vernadsky and Rubakin had their original attitude towards library work in the country. V. Vernadsky sent regularly scientific books and journals to Rubakin in Switzerland. Rubakin came into contact with Georgy, V. Vernadsky’s son, who was living in the U.S. Almost Vernadsky’s every scientific achievement and social merits were acknowledged officially, unlike N. Rubakin who had no academic honors at all. Nevertheless, their contribution to the Russian and world culture is of the same value