Harriet the Spy, by Louise Fitzhugh, 1964

11-year old Harriet M. Welsch, don't forget the "M," craves order in her universe. Her existence is tethered to unalterable constants: a tomato sandwich every day for lunch, cake and milk after school, a notebook ever ready for recording her observations on human nature, and the watchful hawkeye of her nurse, Ole Golly. As spy-cum-authoress in training, she pours her acid wit into her notebooks, but when marriage yanks Ole Golly away, and friends-turned-traitors lay hands on a notebook, Harriet's universe unhinges, and then anything is possible. A thoughful, hilarious, sympathetic, multi-layered narrative with startlingly real characters and troubles; underhandedly offers a wry commentary on excess, privilege and their childhood casualties. Harriet the heroine bursts out of the page and won't soon be forgotten. Most strongly recommended.