I want to know the answer to the following question:
How many volumes was Waitz work?
All the background I'm provided with is that "His interest was mainly in Biological anthropology, but a German philosopher specializing in psychology, Theodor Waitz, took up the theme of general and social anthropology in his six-volume work, entitled Die Anthropologie der Naturvölker, 1859–1864.". Is that enough to answer the question?