MacKenzie, John M.: The empire of nature: hunting, conservation, and British imperialism. Manchester, UK New York New York 1997. Internet: https://books.google.de/books?id=GwPpAAAAIAAJ&printsec=frontcover&dq=The+Empire+of+Nature.+Hunting,+Conservation+and+British+Imperialism.&hl=en&sa=X&ved=0ahUKEwixxPnkrrDTAhVMXhoKHWpnCTAQ6AEIJDAA#v=onepage&q&f=false.