615.1 Y Youngken, Heber Wilkinson, 1885- A text book of pharmacognosy, by Heber W. Youngken … 4th. ed. Rev. and enl., with 469 illustrations containing about 1500 figures. Philadelphia, P. Blakiston´s son & co., inc. [c 1936]. xiv, 924 p. illus. 24 cm. Bibliography: p. 873.