Oz is a 16-book series with 14 primary works first released in 1900 with contributions by L. Frank Baum, Ella Okstad, and 30 others.
1900 • 319 Readers • 160 pages • 3.8
1904 • 34 Readers • 192 pages • 3.6
1908 • 34 Readers • 221 pages • 2.9
1910 • 29 Readers • 300 pages • 3
1913 • 23 Readers • 340 pages • 2.8
1913 • 7 Readers • 169 pages • 3
1917 • 19 Readers • 304 pages • 3
1918 • 18 Readers • 272 pages • 3.1
1919 • 17 Readers • 269 pages • 3