Today I saw on a group shop a Big Little Book called Major Matt Mason Moon Mission published in 1968. I recall having it in early 70s, not sure if a first edition or reprint. I was 5 to 6 years old, editions would have meant nothing to me then.
I perused the book at the shop hoping the plot would jump out at me and I would recall it. I saw it was with a giant bunny. I found one of the giant bunny pages online.