"Internal argument": In the sense of Williams [Williams, E., 1980, “Argument Structure and Morphology”, University of Massachusetts], all obligatory (i.e. lexically specified) arguments with the exception of the subject are internal. For example, "give" and "elect" have two internal arguments; "put" has both an NP and a Locative as internal arguments; and a preposition like "during" has one internal argument.
- Lieber (2004), a pag.215

Marantz [Marantz, A., 1981, ‘On the Nature of Grammatical Relations’, MIT Cambridge] [...] argues that only internal arguments are the arguments of the verb (or preposition) [...].
- Lieber (2004), a pag.245