The drug trade and the book trade.
Helfand
William H
WH
D001879:Bookselling / Q000191:economics / Q000266:history / Q000379:methods / Q000639:trends; D002377:Catalogs as Topic; D002380:Catalogs, Drug as Topic; D004739:England; D000077406:History of Pharmacy; D049670:History, 17th Century; D049671:History, 18th Century; D049672:History, 19th Century; D010604:Pharmacy / Q000379:methods / Q000639:trends; D014481:United States