Baby Sitters Club 18 20 Mystery 10 Author:Ann M. Martin This is three paperback books in the Babysitters Club series:
#18, Stacey's Mistake,ISBN 0590415840
#20, Kristy and the Walking Disaster,ISBN 0590437224
Mystery #10, Stacy and the Mystery Money,ISBN 0590456962
They have quite a bit of cover wear, but the inside pages are in good shape.