Clark, Colin, 1905- The economics of subsistence agriculture, by Colin Clark and Margaret Haswell. - 4th ed. - London, New York, Macmillan; St. Martin's P., 1970. - xiv, 267 p. illus. 22 cm. ISBN: 0333036883 LCCN: 75121341 LC Class. No.: HD1411 .C57 1970 / .C57 1970 Dewey Class. No.: 338.1