Georges Dumézil
Littleton's 1965 PhD dissertation was published in 1966 under the title "The New Comparative Mythology: An Anthropological Assessment of the Theories of Georges Dumézil". He played an important role in disseminating Dumézil's theories Trifunctional hypothesis to an English-speaking audience. Littleton's work on the theories of Dumézil is still considered the most comprehensive source on the subject.