Their differences also became personal; Lenin was particularly angered when Stalin was rude to his wife Krupskaya during a telephone conversation. In the final years of his life, Krupskaya provided governing figures with Lenin's Testament, a series of increasingly disparaging notes about Stalin. These criticised Stalin's rude manners and excessive power, suggesting that Stalin should be removed from the position of general secretary. Some historians have questioned whether Lenin ever produced these, suggesting instead that they may have been written by Krupskaya, who had personal differences with Stalin; Stalin, however, never publicly voiced concerns about their authenticity.