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| | American Zoo and Aquarium Association (Site not responding. Last check: 2007-11-06) |
 | | Dean, J.M. The 2000 survey for the presence of the Oregon silverspot butterfly, Speyeria zerenehippolyta (Lepidoptera, Nymphalidae), on the Clatsop Plains, Clatsop County, Oregon. |
 | | Eid, N. The 1999 survey for the presence of the Oregon silverspot butterfly, Speyeria zerene hippolyta (Lepidoptera, Nymphalidae), on the Clatsop Plains, Clatsop County, Oregon. |
 | | Peterson, M. The 2002 survey for the presence of the Oregon silverspot butterfly, Speyeria zerene hippolyta (Lepidoptera, Nymphalidae), on the Clatsop Plains, Clatsop County, Oregon. |
| www.aza.org /ConScience/OregonSilverspot (1510 words) |
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