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Scitable (Scitable is a free science library and personal learning tool brought to you by Nature Publishing Group and currently concentrates on genetics and cell biology) https://www.nature.com/scitable
Tree of Life (Information about the diversity of organisms on Earth, their evolutionary history (phylogeny), and characteristics) http://tolweb.org/tree/
Health & Environmental Research Online (HERO contains the key studies EPA uses to develop environmental risk assessments for the public. EPA uses risk assessments to characterize the nature and magnitude of health risks to humans and the ecosystem from pollutants and chemicals in the environment) hero.epa.gov/hero/