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| Encyclopedia Smithsonian - http://www.si.edu/Encyclopedia_SI/ Search over 2 million records with images, video and sound files, electronic journals and other resources from the Smithsonian's museums, archives and libraries. |
| New World Encyclopedia - http://www.newworldencyclopedia.org Designed to organize human knowledge so the reader will learn information not just for its own sake, but for its value to the reader and the world as a whole. |
| Plantspedia.org - http://plantspedia.org/ A free encyclopedia of plants with around 90,000 plants listings. |