Schlippé, Pierre de. Shifting cultivation in Africa : the Zande System of Agriculture / Pierre de Schlippé. - London : Routledge and Kegan Paul, 1956. - xxxi, 304 p. : ill. ; 22 cm. Includes index. 344 344 Subjects--Topical Terms: Shifting cultivation--Central--Africa. Dewey Class. No.: 572.7 / D454s