英文文献：Coca Substitijtion In Bolivian Agriculture: Political Economy Or Expediency?
英文文献作者：Whitaker, Morris D.,Villegas, Clovis
英文文献摘要：
In recent years, illegal consumption of cocaine in the United States has increased dramatically from levels which have been described as" ... insignificant ... " in the early 1960s (DCDATF, p. 24). Cocaine is produced from the leaf of the coca plant which is native to the subtropical river valleys of the eastern slopes of the Andes, and which has been adapted to their piedmont. It ranges from Colombia on the north through Bolivia on the south, although Bolivia and Peru are the most important producers. Coca leaf is harvested from three to four times a year depending on its location and provides a steady flow of income relative to alternative crops which are harvested annually. Historically, most coca leaf has been consumed by chewing or as a medicinal tea with small quantities made into cocaine under government license.