The Phantom Friend

The Judy Bolton books, written by Margaret Sutton, were a popular girls mystery series. Judy Bolton is in many ways a complex and believable role model for girls, primarily because of their realism and social commentary. Judy was also unique in that halfway through the series, she got married (something series book heroines rarely, if ever, did). The first 4 volumes were published in 1932. The series continued until 1967 and consisted of 38 volumes. Each book was "based on something that actually happened" and many were also based on real life sites.