Mark Yashar's Profile > Mark's Groups

Fans of Arthur C. Clarke
104 members — last activity Jun 01, 2019 11:56AM
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Hard SF
1193 members — last activity 20 hours, 29 min ago
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Goodreads Authors/Readers
56301 members — last activity 1 hour, 4 min ago
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The Evolution of Science Fiction
1878 members — last activity 14 hours, 18 min ago
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Sci-fi and Heroic Fantasy
8791 members — last activity 2 hours, 29 min ago
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Science and Inquiry
4495 members — last activity Mar 23, 2026 12:32PM
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Science and Natural History
1134 members — last activity Sep 22, 2020 01:21PM
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Astronomy and Space exploration
290 members — last activity Feb 23, 2026 02:08AM
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