Betsy-Tacy is a 9-book series with 9 primary works first released in 1940 with contributions by Maud Hart Lovelace and Lois Lenski.
1940 • 19 Readers • 122 pages • 3.9
1942 • 4 Readers • 192 pages • 4.7
1943 • 3 Readers • 244 pages • 4.3
1946 • 2 Readers • 352 pages • 4
1952 • 3 Readers • 388 pages • 4.3