In the weeks leading up to the September 27, 1962, publication, there was strong opposition to "Silent Spring" from the chemical industry. DuPont (a main manufacturer of DDT and 2,4-D) and Velsicol Chemical Corporation (exclusive 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 as well as "The New Yorker" and "Audubon" unless the planned "Silent Spring" features were canceled. Chemical industry representatives and lobbyists also lodged a range of non-specific complaints, some anonymously. Chemical companies and associated organizations produced a number of their own 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 endorsing the book by William O. Douglas).