The author offers the brief biographical information on Rujero Sergeevich Gilyarevsky whose 90-th anniversary is celebrated. She reviews the main stages of his academic and pedagogical career, in particular, his scholarly works, his two theses studies (candidate’s and doctoral), numerous publications that have been contributing to the librarianship, library and information sciences. The author emphasizes the scope of Gilyarevsky’s professional interests and retraces expanding of the subject scope of his publications – from catalog structuring (1954) to cloud technologies, information management and scientometrics. Rujero Gilyarevsky analyzes the problems of the libraries (and e-libraries, in particular), their future, professional values of the librarians within the digital communication environment, bibliography as an element of information culture. R. Gilyarevsky has complete mastery of several foreign languages. The selected bibliography of R. Gilarevsky’s publications, including those co-authored by his colleagues, is appended.