He was able to combine the manuscript of a lecture delivered by Prof. F.M.Th. Böhl with the glass slides that were shown as illustrations. The lecture was first held in 1920, when Böhl taught at Groningen, and repeated in 1927 or later, when he had been appointed at Leiden.
As Dr De Klerk notes, it is one of the few lecture texts found by the “Projecting Knowledge” project that can be combined with the accompanying, projected glass slides in the same collection. He has put text and illustrations of this lecture side by side in one document, which you can access from this page: ‘De oude Babylonisch-Assyrische beschaving’ door F.M.Th. Böhl, Groningen, 10 december 1920 & Leiden, >1927.