After his retirement , he went on to publish more than 200 articles , in a variety of journalsâ '' more than some reputable scientists publish in their entire careers ; 14 of his 25 books were published after he was 65 . Following his retirement , he went on to publish more than 200 articles , in a variety of journalsâ '' more than some reputable scientists publish in their entire careers ; 14 of his 25 books were published after he was 65 .