Beginning in 1970 , Heinlein had a series of health crises , broken by strenuous periods of activity in his hobby of stonemasonry : in a private correspondence , he referred to that as his " usual and favorite occupation between books " . The decade began with a life-threatening attack of peritonitis , recovery from which required more than two years , and treatment of which required multiple transfusions of Heinlein 's rare blood type , A2 negative . < ! -- In the mid-1970s , Heinlein wrote two articles for the '' Britannica Compton Yearbook '' . He and Ginny crisscrossed the country helping to reorganize blood donation in the United States in an effort to assist the system which had saved his life . At science fiction conventions to receive his autograph , fans would be asked to co-sign with Heinlein a beautifully embellished pledge form he supplied stating that the recipient agrees that they will donate blood . He was the guest of honor at the Worldcon in 1976 for the third time at MidAmeriCon in Kansas City , Missouri . At that Worldcon , Heinlein hosted a blood drive and donors ' reception to thank all those who had helped save lives
MidAmeriCon
34th World Science Fiction Convention
Robert A. Heinlein