Dr Armbruister was the senior librarian on the Braxiatel Collection. He had a reputation for "treating defaulting borrowers with severity".
The Assistant Librarian notified Bernice Summerfield when Jason Kane had several overdue library books and told her that Dr Armbruister had been recruiting several large volunteers to "visit" Jason to remind him of his obligations. (PROSE: Sex Secrets of the Robot Replicants)