Sobol, Donald J.

Fifth-grader "Encyclopedia" Leroy Brown solves ten mysteries and, by putting the solutions at the back of the book, challenges the reader to do the same.

Four boys go on a mission as secret agents to help rid their city of enemy spies.

Well-known detective, Encyclopedia Brown, solves the mysterious disappearance of rich Mr. Butler.

Several boys chase a suspicious man who turns out to be a spy, so the boys form society VACUUM which will aid a national organization of secret agents in apprehending other spies.

An account of the everyday life in medieval England including a description of the feudal system, knighthood life in the towns, manors, and church. Also describes the schools, clothing, and transportation.