The Houston Press's 2011 coverage of Comicpalooza included this shot of a beautiful letter of appreciation from Ray Bradbury to Robert Heinlein, written in 1976.
YOUR INFLUENCE ON US ALL, FROM 1939 ON, CANNOT BE MEASURED. I CAN ONLY SAY I REMEMBER, WARMLY, YOUR MANY KINDNESSES TO ME WHEN I WAS 19–20–21 YEARS OLD. THAT YOUNG MAN BASKED IN YOUR LIGHT AND WILL CONTINUE TO BE GRATEFUL FOR THE HELP YOU OFFERED WHEN I WAS SO POOR & NEEDFUL! YOURS IN THAT MEMORY — RAY BRADBURY
AUG – 1976
The wonderful thing for me is that when I was 19-20-21, I, too, found many writers who were graceful and helpful to me and my writing, from Judith Merril and Damon Knight to James Patrick Kelly and Nancy Kress. Science fiction has always been a place where debts are paid forward.