Best we can normally hope for in these situations is someone gets a newspaper advert or electronics company flyer/catalogue from the relevant timeframe and finds what they stocked, as well as what they didn't, and also hope they did not import a few titles from elsewhere. As they are of some interest to a lot of people then people do scan them in fairly frequently but I don't know German and the electronics vendors of West Germany well enough to start such a search.
"earliest example of porn"
An ivory statuette of a well-endowed woman discovered in Germany suggests that humanity's earliest art might have been of the erotic variety. Digging in a cave near Stuttgart last fall, University of Tübingen archaeologist Nicholas Conard unearthed what he says is the most ancient representation of a human female yet found--and, at more than 35,000 years old, one of the oldest sculptures ever discovered.