Who is Gertrude and Hilda from Women and what is their importance?

Gertrude is a twenty-two-year-old German, who is described as very thin. She and her friend, Hilda, have been traveling through the United States on an extended vacation. Each of the girls has read Henry Chinaski's work translated into German, although they both speak English.

Hilda and Gertrude visit Henry's apartment in Los Angeles where they engage him in hard drinking, smoking, and group sex. They remain at Henry's apartment for a few days before meeting a wealthy man who offers them jobs, probably in the pornographic film industry. Henry drives them to a ritzy estate and drops them off.