Describing his juvenile novel Letters from Terra, Van Veen (the narrator and main character in VN’s novel Ada, 1969) mentions Theresa and Antilia Glems, the characters in his novel:
Ada’s letters breathed, writhed, lived; Van’s Letters from Terra, ‘a philosophical novel,’ showed no sign of life whatsoever.
(I disagree, it’s a nice, nice little book! Ada’s note.)