Sherlock Holmes#1, 1975 Published by DC is his first solo series with that publisher. I would suggest this be upgraded to a minor key.
If it were also his 1st app I would say a Gold Key, but his 1st app in DC was made much earlier.
However, I do believe this book, written by Dennis O’Neil is his series premiere deserves at least a minor key.
This is My very first post so please forgive Me if I did anything wrong.
Thank You