Found:

Avoid Pronoun Principle

SYNTAX: a principle which states: 'Avoid Pronoun'. This principle, which is considered a subcase of a conversational principle ('don't say more than is required'), is invoked to impose a choice of PRO over an overt pronoun where possible. EXAMPLE: the principle explains why his in (i) does not refer to John, unless it is stressed.

(i) John would much prefer his going to the movie