Luhmann wrote prolifically, with more than 70 books and nearly 400 scholarly articles published on a variety of subjects, including law, economy, politics, art, religion, ecology, mass media, and love. While his theories have yet to make a major mark in American sociology, his theory is currently well known and popular in German sociology, and has also been rather intensively received in Japan and Eastern Europe, including Russia. His relatively low profile elsewhere is partly due to the fact that translating his work is a difficult task, since his writing presents a challenge even to readers of German, including many sociologists. (p. xxvii Social Systems 1995)