Russian scholar and bibliographer; born at Homel, government of Moghilef, about the middle of the nineteenth century. He is known especially as the author of "Ḳiryat Sefer," or "Bibliotheca Hebraica Post-Mendelssohniana" (Leipsic, 1891-95), a bibliographical dictionary of modern Hebrew literature from the beginning of Mendelssohn's epoch until 1890. The compilation of this work occupied Zeitlin for twenty years. Hemade extensive use of Benjacob's "Oẓar ha-Sefarim" and of Fürst's "Bibliotheca Judaica," and visited Wilna and Warsaw, the centers of the Hebrew book market, as well as many university cities—as Königsberg, Berlin, Geneva, and Paris—from the libraries of which he gathered additional material for his work. The "Ḳiryat Sefer" indexes not only works in book form, but also important periodical articles, biographical sketches, and scientific essays, in addition to giving biographical notes on several authors. Zeitlin had previously prepared an index of works written on the Jewish calendar, in which he enumerates seventy-seven Hebrew works; this index was published by Ḥayyim Jonah Gurland in "Yevreiski Kalendar" (St. Petersburg, 1882). In the "Zeit. für Hebr. Bibl." (ix. 3-4) Zeitlin has recently published an alphabetical list of anagrams and pseudonyms of modern Hebrew writers; and he is a contributor to several Hebrew periodicals, writing mostly biographical articles.