On the Internet there is no telling what you will find. Ricardo Franco has recently been very active posting links to the Manichaean discussion forum at Yahoogroups, a lot of what he offers I have seen or read before, but Die Buddhistische Spätantike in Mittelasien–Die manichaeischen Miniaturen – by A. Von Le Coq is a new one for me. I have studied, rather than read, Hans Joachim Klimkeit’s monography on Manichaean calligraphy and iconography and got an impression of the “field” of Manichaean iconography – but the name Le Coq was new to me. Apparently it was published in Berlin in 1923.
The book in question is in German, but with tools like Babelfish it is possible to get an arbitrary impression of the contents, if you like me do not understand the language. It is presented in high resolution scans of the pages, but it features a useful OCR representation of the contents.
The book was published by the Digital Silk Road Project in Japan which has made a lot of material from the two centuries of archeological digs in the wide cultural and geographical area of the ancient Silk Road.The illustrations, of which there are few, but which are rare indeed, is nevertheless worth a tour of the book.