- Libro electrónicoA Walk in the Desert, 2nd EditionRebecca L. Johnson
- Libro electrónicoA Walk in the Deciduous Forest, 2nd EditionRebecca L. Johnson
- Libro electrónicoA Walk in the Boreal Forest, 2nd EditionRebecca L. Johnson
- Libro electrónicoA Walk in the Prairie, 2nd EditionRebecca L. Johnson
- Libro electrónicoA Walk in the Tundra, 2nd EditionRebecca L. Johnson
- Libro electrónicoA Walk in the Rain Forest, 2nd EditionRebecca L. Johnson