The results of the exploratory expeditions cried out for presentation in map form, and PGM published exploration results as quickly and accurately as possible. Petermann had all results he received from explorers checked against the considerable information and maps available in the Perthes Institute. This fund of knowledge grew to be so large that the Institute soon had a large library of manuscripts, books, atlases, and maps at its disposal that could vie with any university or society collection. In the 1980s it was thought that the Perthes-archives contained 180,000 printed maps and around 2,800 atlases. In the 1990s the estimate was 1,000 m of archive, some 400,000 maps (including manuscripts), and some 120,000 geographical works. All collections (currently estimated at 185,000 sheets of maps, 120,000 geographical works, and 800 m of archives) were acquired in 2003 by the Free State of Thüringen and deposited with the library of the University of Erfurt in its research center in Gotha.