A Neoproterozoic Snowball earth, Hoffman et al, Science 1998 (This is the paper that reignited the Snowball Earth ideas)

Snowball earth, Hoffman and Shrag, Scientific American 2000

Hoffman and Shrag, 2000, "Snowball Earth" - Harvard

A curve ball to the Snowball Earth Hypothesis (critical)

Paleoclimatology: Snowball Fights, 2002, Lubick, Nature (critical)