Dobroslav Ružić (Čačak, 1854 – Kruševac, 1918) studied Natural Sciences in Munchen and Yen, then he was a high school Professor in several Serbian towns. He translated from German Language, and wrote about Hein. He was a notable cultural and national workman. He worked as a librarian in the National Library of Serbia and in the Royal Library in Belgrade. In the National Library of Serbia (1901 – 1903), he was arranging and inventorying the manuscript materials and he with drawed the old and rare books. The arrangement of the Holdings of the Royal Library was entrusted to him, as he was an expert in library theory and practice, and he did it with a lot of success. During the First World War, he took the the «Miroslavljevo Jevandjelje» (Miroslav Gospel) from the representative collections of the national treasures, and gave the Manuscript to a special care and preservation. In the large bibliographical works of Dobroslav Ružić, we can separate 36 bibliographical records from the Library Science. The most important work is the abstract of the Dispute/Review on Libraries (first edition 1901, second 1922), where he has written about the state of the worldwide Libraries.