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59 pages first pub 1997 (editions)

nonfiction science challenging informative medium-paced
Other editions (3)
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360 pages first pub 2010 (editions)

nonfiction science challenging informative medium-paced

72 pages first pub 2010 (editions)

nonfiction science challenging informative medium-paced

360 pages first pub 2010 (editions)

nonfiction science challenging informative medium-paced