Sarah and Katie by Dori White, TX2378, 1st Scholastic paperback printing, 1972, 168 pages. Illustrated by Trina Schart Hyman.
DESCRIPTION: “Sarah can’t believe that someone in her class stole the teacher’s diamond ring. And now the principal suspects her. If only Sarah could ask Katie to help solve the mystery. But Katie is still angry with her. Then a secret phone call gives Sarah a clue.” (from the back cover)