Extract all the names of people that Betty worked with from the text.

Context: Betty Branch earned her Bachelor of Arts in Studio Art and Master of Arts in Liberal Studies from Hollins University and completed additional studies with artists Denis Knight and Georgiana Mailoff, and at Miles and Generalis Sculptural Services. She lives and works in Roanoke, Virginia. Her first retrospective exhibition, Betty Branch: Through the Crow's Eye, a Retrospective, presented the artist's work in bronze, marble, porcelain, works on paper, and performance pieces.

Answer: Denis Knight, Georgiana Mailoff