the Second Polish Republic. The early YIVO also had branches in Berlin, Warsaw and New York City. Over the next decade, smaller groups arose in many of the other countries with Ashkenazi populations. In YIVO's first decades, Tcherikover headed the historical research section, which also included Simon Dubnow, Saul M. Ginsburg, Abraham Menes, and Jacob Shatzky. Leibush Lehrer (1887–1964) headed a section including psychologists and educators Abraham Golomb, H. S. Kasdan, and Abraham Aaron Roback. Jacob Lestschinsky (1876–1966) headed a section of economists and demographers Ben-Adir, Liebmann Hersch, and Moshe Shalit. Weinreich's language and literature section included Judah Leib Cahan, Alexander Harkavy, Judah A. Joffe, Zelig Kalmanovich, Shmuel Niger, Noach Pryłucki, and Zalman Reisen. YIVO also collected and preserved ethnographic materials under the direction of its Ethnographic Committee. In 1925, YIVO's honorary board of trustees or "Curatorium" consisted of Simon Dubnow, Albert Einstein, Sigmund Freud, Moses Gaster, Edward Sapir and Chaim Zhitlowsky. From 1934 to 1940, YIVO operated a graduate training program known as the Aspirantur. Named after Zemach Shabad, YIVO's chairman, the program held classes and guided students in conducting original research in the field of Jewish studies. Many of the students' projects were sociological in nature (reflecting the involvement of Max Weinreich) and gathered information on contemporary Jewish life in the Vilna region. The Nazi advance into Eastern Europe caused YIVO to move its operations to New York City. A second important center, known as the Fundacion IWO, was established in Buenos Aires, Argentina. All four directors of YIVO's research sections were already in the Americas when the war broke out or were able to make their way there. The organization's new headquarters were established in New York City. A portion of the Vilna archives was ransacked by the Nazis and sent to Frankfurt to become the basis of an anti-Semitic department of the Nazis' planned university. In 1946, the U.S. Army recovered these documents and sent them to YIVO in New York. The YIVO Library was looted by the Germans and the ERR, but an organization that called itself "The Paper Brigade" were able to smuggle out many books and preserve them from destruction. These materials were then saved from the Soviets by a Lithuanian librarian, Antanas Ulpis. These materials are now held in the Lithuanian Central State Archives and Martynas Mažvydas National Library of Lithuania. In 2014, with the cooperation of the government of the Republic