A number of sources mention Project Gleem which supposedly was an earlier version of the Blue Book Project. (Other projects were: Grudge, Pounce and Sign).
It should be noted, though, that only Sign and Grudge are mentioned in official documentation as predecessors of Blue Book, and this is what the majority of researchers accept.
One source, Robert Collins, in a message posted on the Internet, claims Project Gleem was the predecessor or the initial name of the Aquarius project.
Aquarius project ~ Blue Book ~ Grudge project ~ Pounce project ~ Secret projects ~ Sign project ~