#1 Paul (P.C.) Doherty has published under several pseudonyms, including Michael Clynes, C. L. (or Celia L.) Grace, Paul Harding, Ann Dukthas, and Anna Apostolou, but now writes under his own name.
#2 Paul Doherty is the Director of the Exploratorium Teacher Institute and wrote The Spinning Blackboard and Other Dynamic Experiments on Force and Motion.
#3 Paul Doherty1947- wrote Building and Using an Astronomical Observatory.
#4 The fourth Paul Doherty is very probably a mistake, since "Messen Berechnen Computern" is part of an 8-volume German encyclopedia for young adults published in the 1980s.