The "euthanasia campaign" of mass murder gathered momentum on 14 January 1940 when the "handicapped" were killed with gas vans and killing centres, eventually leading to the deaths of 70,000 adult Germans. Professor Robert Jay Lifton, author of "The Nazi Doctors" and a leading authority on the T4 program, contrasts this program with what he considers to be a genuine euthanasia. He explains that the Nazi version of "euthanasia" was based on the work of Adolf Jost, who published "The Right to Death" (Das Recht auf den Tod) in 1895. Lifton writes: