For the pu-ch'ü I used in addition Yang Chung-i, H. Maspero, E. Balazs, W. Eichhorn.

The philosophical trends of this period have been analysed by E. Balazs.

Mention should also be made of the aesthetic-philosophical conversation which was fashionable in the third century, but in other form still occurred in our period, the so-called "pure talk" (ch'ing-t'an) (E. Balazs, H. Wilhelm and others).

p. 173: The best comprehensive study of T'ang economy in a Western language is still E. Balazs's work.

The tax reform of Yang Yen has been studied by K. Hino; the most important figures in T'ang economic history are Liu Yen (studied by Chü Ch'ing-yüan) and Lu Chih (754-805; studied by E. Balazs and others).