Incoming Resources
- Made available electronically by NetLibrary, Boulder, Colo., 2009
- VeloPress, Boulder, Colo., 2010
- Sharp End Publishing, LLC, Boulder, Colo., 2017
- AudioGO, North Kingstown, R.I., Boulder, Colo., 2011
- Big Kid Science, Boulder, Colo., 2012
- Sounds True, Incorporated, Boulder, Colo., 2011
- Velo Press, Boulder, Colo., 2011
- Sounds True, Boulder, Colo., 2021