Rikker's blogpost on his starting of the Thai Gutenberg project made me rediscover one book in the Thammasat Electronic Rare Books site titled "การตั้งกิ่งอำเภอในประเทศสยาม", which translates to "Creation of minor districts in the country of Siam". It was published in 1938 by Thanom Vibunmongkhon (ถนอม วิบูลย์มงคล), who was province governor in the 1940s in Pathum Thani, Chanthaburi and Prachuap Khiri Khan. So this short 35 page publication was maybe something like his graduation paper when beginning his career in the bureaucracy.
I have no idea if this work is already in the Public Domain - according to Thai law 50 years after the death of the author, but I haven't found any more details about Thanom than those three governor posts - but would love it if this book would be really digitized now. While the scanned PDF is of course better than nothing, having it as a Thai text file would allow many more things like searching for words or, especially useful for me struggling with learning Thai, copy-and-paste it to Google Translate for a first overview or copy words to the Longdo dictionary. But I somehow doubt an OCR software would work on that font used in the book, at least a native Thai proofreader would be mandatory.
The parts which I could understand in that document already were a few Royal Gazette announcements copied verbatim as examples, i.e. the creation of Wang Nuea in 1938 [Gazette], the creation of minor districts in Monthon Udon in 1926 [Gazette] - the latter even with a wrong signature date of 1917 (2460) instead of 1926 (2468).