Arthur S. Hoffman and the famous boy's series he influenced

I asked a question in the previous post
about Arthur S. Hoffman:

Which
unknown writer was initially rejected by Hoffman, but took his advice in the
rejection letter; went on to contribute to Adventure, and later author many
books in a famous series for boys? Put your guesses, answers in comments.

Nobody guessed the right answer, maybe y'all knew it already. Anyway, the right answer is Leslie McFarlane, and the
series is the Hardy Boys,
which you may have come across. From The Secret of the Hardy Boys: Leslie McFarlane and the Stratemeyer
Syndicate by Marilyn S. Greenwald:

The
detailed comments from Adventure editor Arthur Sullivant Hoffman, in particular,
left him so depressed that he was tempted to take a walk after reading
it—”straight into the lake,” he joked in his autobiography. After the initial
shock, however, Les was smart enough to reread the criticisms and profit from
them: “I realized that this was advice with a value beyond rubies. Mr. Hoffman was
an editor who wasn’t above taking time out to give a hand to a beginner who
needed help. What he had done, simply; was to save this beginner about two years
of trial and error." Even as a young man, Les was determined and practical. He
listened to criticism and took it in the spirit in which it was given—a quality
that would reap benefits throughout his life.