CK-12 Foundation
Ck 12: Earth Science: Star Power Study Guide
[Free Registration/Login may be required to access all resource tools.] This study guide summarizes key points about the energy in stars. Includes a few questions to check for understanding.
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The Sustainable Scale Project: Ecological Footprint
The Ecological Footprint is rooted in the fact that all renewable resources come from the earth. It accounts for the flows of energy and matter to and from any defined economy and converts these into the corresponding land/water area...