Other historians, such as D. D. Guttenplan, Jeff Kisseloff, and Amy Knight, however, assert that "Spies" conclusions were not borne out by the evidence and accused its authors of engaging in "shoddy" research. Guttenplan stresses that Haynes and Klehr never saw and cannot even prove the existence of the documents that supposedly convict Hiss and others of espionage, but rather relied exclusively on handwritten notebooks authored by Vassiliev during the time he was given access to the Soviet archives in the 1990s while he collaborated with Weinstein. According to Guttenplan, Vassiliev could never explain how he managed, despite being required to leave his files and notebooks in a safe at the KGB press office at the end of each day, to smuggle out the notebooks with his extensive transcriptions of documents. Haynes and Klehr respond that the material was examined by historians, archivists, and intelligence professionals who unanimously agreed that the material was genuine.