Help! I'm a prisoner in the library!

Ethel Clifford Rosenberg, known professionally as Eth Clifford or Ruth Bonn Penn, was an American children's fiction writer, best known as the author of the Flatfoot Fox and Jo-Beth and Mary Rose Mysteries series. Clifford's husband, David Rosenberg, encouraged her to begin writing, and she did so, publishing her first novel for adults in 1949. Her subsequent books were written for children, and her 1979 novel Help I'm A Prisoner in the Library! earned her the prestigious 1982 Young Hoosier Award. Together with her husband, she founded David-Stewart Publishing company. When co-authoring a book, the two would write under the portmanteau pen name of David Clifford. Source: [Wikipedia](