This set includes all the Book Study books used with The Purple Learning Language Arts Through Literature Program:   

Farmer Boy - Laura Ingalls Wilder  ISBN: 0064400034

The Trumpet of the Swan - E.B. White ISBN: 0064408671

Meet Addy - Connie Porter ISBN: 1562470752

Caddie Woodlawn - Carol Ryrie Brink  ISBN: 0689713703