Betsy-Tacy is a 8-book series with 8 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 • 240 pages • 4.3
1952 • 3 Readers • 321 pages • 4.3