1952 is often thought of as Topps 1st baseball card set, but it was not.
Topps issued several smaller baseball card sets prior to their huge 1952 set.
Topps buzz word was "BIGGER is BETTER" for their 1952 Topps set which Topps described as: "GIANT IN BOTH SIZE and NUMBER of CARDS" (407).

Key card in the 1952 Topps set is #311 MICKEY MANTLE. Often called Mickey Mantle's Rookie card - BUT IT IS NOT. That honor goes to his 1951 Bowman.
1952 Topps "High Numbers" (#311-#407), are very, very scarce with an interesting story:
This HUGE set was released in series weeks apart. By the last (6th) series, baseball season was over and football starting. Candy shops had plenty of baseball cards from earlier series so most cancelled their orders for the last series creating the scarcity.

Adding interest is how Topps disposed of the now un-needed cards including THOUSANDS of 1952 Topps MICKEY MANTLE's. They dumped them into the Atlantic Ocean like most of New York's trash in those days.