Who is selma thurmer from The Catcher in the Rye?

Selma Thurmer is the wife of Mr. Spencer, who is Holden Caulfield's history teacher at Pencey Prep in the novel "The Catcher in the Rye" by J.D. Salinger. She is described as a friendly and amiable woman who greets Holden warmly when he goes to visit Mr. Spencer.