| Underwater World |
2007-09-01 |
26 |
| Unique Pets |
2012-09-01 |
7 |
| United States |
2009-09-01 |
54 |
| United States Armed Forces |
2011-09-01 |
7 |
| United States Encyclopedias |
2023-12-15 |
5 |
| United States President Biographies |
2016-12-15 |
3 |
| United States President Biographies (Abdo Kids Jumbo) |
2014-08-01 |
7 |
| United States Presidents |
2009-01-01 |
94 |
| United States Presidents *2017 |
2016-08-15 |
45 |
| United States Presidents (Checkerboard Library) |
2016-08-15 |
1 |
| Universe |
2008-01-01 |
18 |
| Unsolved Mysteries |
2007-09-01 |
16 |
| Unusual Pets |
2013-01-01 |
7 |
| Up2U Adventures |
2013-09-01 |
12 |
| Up2U Adventures Set 3 |
2017-09-01 |
5 |
| Ursula's Funland |
2017-09-01 |
5 |
| U.S. Armed Forces |
2014-08-01 |
7 |
| US Armed Forces |
2018-12-15 |
7 |
| US Landmarks |
2016-12-15 |
7 |
| US Military Careers |
2020-08-01 |
7 |
United States Encyclopedias
World of Mythical Beings
Captives of the Reich