In the weeks before the September 27, 1962, publication, there was strong opposition to "Silent Spring" from the chemical industry. DuPont, a major manufacturer of DDT and 2,4-D, and Velsicol Chemical Company, the only manufacturer of chlordane and heptachlor, were among the first to respond. DuPont compiled an extensive report on the book's press coverage and estimated impact on public opinion. Velsicol threatened legal action against Houghton Mifflin, and "The New Yorker" and "Audubon Magazine" unless their planned "Silent Spring" features were canceled. Chemical industry representatives and lobbyists lodged a range of non-specific complaints, some anonymously. Chemical companies and associated organizations produced brochures and articles promoting and defending pesticide use. However, Carson's and the publishers' lawyers were confident in the vetting process "Silent Spring" had undergone. The magazine and book publications proceeded as planned, as did the large Book-of-the-Month printing, which included a pamphlet by William O. Douglas endorsing the book.