Henry, I am not quite sure whether anything much more exists about Klages or by him in English. However, he was a philosopher and psychologist of some importance even outside graphology. The connection between Klages and graphology has been damaging for his appreciation as a philosopher and psychologist on his own right. Graphology is very unpopular as a scientific method method because it is so subjective, even if it might have some value as a diagnostic tool. This fact has led to an undervaluation of Ludwig Klages as a psychologist. However, Klages has published much on characterology and philosophy, but to my knowledge his books have hardly been translated into English. If I am wrong, please correct. He has written one textbook on characterology, and a large philosophical work "Geist als Widersacher der Seele", among many others.