In 1975, Peter Wellnhofer wrote a classic monograph on the Rhamphorhynchoidea. This set of 3 linked works has been the baseline for the study of this group of pterosaurs since then. It is a well organised work with analysis split into skeletal morphology, systematics and Palaeoecology. The texts were originally in German and as far as I am aware, they have not been translated wholesale into English. Recently, I started to translate part 2 for my own use. I would love to publish my translation, which will be a new work, but the original text is not out of copyright until 2025. I can only find paper copy, but I have been told that there is an electronic copy in German. This has eluded me, so I am transcribing and translating from the original text.
Wellnhofer, P. 1975 Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Teil I. Allgemeine Skelletmorphologie. Paläontographica A 148 , 1–33.11 plates.
Wellnhofer, P. 1975 Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Teil II. Systematische beschreibung. Paläontographica A 148, 132–186.
Wellnhofer, P. 1975 Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Teil III. Palökologie und Stammesgeschichte. Paläontographica A 149, 1–30. 13 plates
The problem in translating any text is the transfer of meaning. There are words in German that can have several possible meanings in English. This also works the other way around. The bulk of the meaning is transferable with a high level of confidence in the result, but there are some areas where the meaning has to be a best guess. This type of translation is often referred to as a Gist Translation. This means that in some cases, the reader may need to refer to the original text to grasp the full meaning of a sentance of passage. It is for this reason that translations should only be attempted from the original documents. Another of Peters texts that I have frequently used is the Handbook of Paleoherpetology, Part 19. This text is also only available in German, so people who are not able to read that language can only look at the wonderful line drawings and be amazed. This is of course, another text that sets the baseline for the study of pterosaurs in general. It is a little dated now, but still a valuable resource. The original text is still available to purchase on the Internet.
Wellnhofer, P. & Khun, O. 1978 Handbuch der Paläoherpetologie. Teil 19. Pterosauria. Stuttgart: Verlag Gustav Fischer.
These texts defined the study of pterosaurs for a whole generation of researchers. It would be beneficial to the subject to have them available on line both in their original German text and in English. The main difficulty is in gaining permission to freely allow access without infringing copyright law. Watch this space!