Mary Louise by L. Frank Baum

The Bluebird Books is a series of novels popular with teenage girls in the 1910s and 1920s. The series was begun by L. Frank Baum using his Edith Van Dyne pseudonym, then continued by at least three others, all using the same pseudonym. Baum wrote the first four books in the series, possibly with help from his son, Harry Neal Baum, on the third. The books are concerned with adolescent girl detectives— a concept Baum had experimented with earlier, in The Daring Twins (1911) and Phoebe Daring (1912)