Pondoro spent quite a few time in Australia, was it at John Dawkins' ? I am checking this. Peter Capstick. A Man Called Lion. Huntington Beach CA, Safari Press, 1994.

For the 2 other ones, I am going to check "White Hunters: The Golden Age of African Safaris" Brian Herne .
W.M. "Bill" Jenvey is depicted page 176-179
Ernest Frank Bowman is depicted page 180-182