Defenders of Mayer argue that his statement that "Sources for the study of the gas chambers are at once rare and unreliable" has been taken out of context, particularly by Holocaust deniers. Michael Shermer and Alex Grobman observe that the paragraph from which the statement is taken asserts that the SS destroyed the majority of the documentation relating to the operation of the gas chambers in the death camps, which is why Mayer feels that sources for the operation of the gas chambers are "rare" and "unreliable".