by John Peterson (1969)
Weasel is after something, and he's going to trick Flying Squirrel to get it. But Flying Squirrel has a friend, Mr. Bat, who isn't going to sit around and let Weasel get away with it!
Astrid Lindgren. [Dt. von Karl Kurt Peters
While three children are waging an imaginary war against their three friends, they find themselves involved in an actual murder case, which they solve with clues revealed by subsequent events of their own war.
Franklin W. Dixon
It's Career Week at Bayport Elementary, and Frank and Joe's school assembly turns up some interesting guests. One student's uncle is an animal trainer who brings a chimpanzee. Another girl's father is an anthropologist who brings in a mask decorated with feathers and shells from a Pacific island. But when the assembly is interrupted by a fire drill, the mask is stolen and the Hardys spring into action.
Carolyn Keene
The Dean of Emerson College enlists Nancy to investigate the thefts of a valuable substance being used in a top-secret experiment. But when Nancy discovers that the experiment involves biological mutations, she knows she must find the culprit before the lives of everyone on campus are endangered.
Jordan Cray
While on a brief vacation in Key West, sixteen-year-old Annie and her stepbrother Nick do an internet search that inadvertently involves them in a dangerous murder mystery.