"This is a 30 page paper published in February of 1939 detailing a December 8, 1938 conference on the subject of gasification for transportation use. It was put out by the (British) Institute of Fuels. It starts out rather general, but then gets very specific, covering every type of gas producer known to (European) man at the time. They describe, with text, pictures and drawings the 4 basic types and give examples from the many manufactures who were making them.
There is lots of data, including gas analyses, reliability, testing, road rally results, etc. There are a couple of large tables comparing various vehicles, by weight class against many criteria that all gasification enthusiasts would recognize. For example, there's a table on cylinder bore wear vs fuel type. Then there's data comparing the "Methods of Gasification" 16 different manufacturers on 10 different attributes. Another table lists fuel usage for 6 "lorries" and a bus, weighing from 1.45 tons to 6.9 tons. There is a rather detailed section wholly devoted to gas purification. 71 references are cited."