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
1200 members — last activity Apr 20, 2026 07:08AM
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Goodreads Authors/Readers
56612 members — last activity 1 hour, 0 min ago
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The Evolution of Science Fiction
1904 members — last activity 15 hours, 0 min ago
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Sci-fi and Heroic Fantasy
8840 members — last activity 13 hours, 20 min ago
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Science and Inquiry
4507 members — last activity May 08, 2026 09:59PM
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Science and Natural History
1135 members — last activity Sep 22, 2020 01:21PM
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Astronomy and Space exploration
297 members — last activity Apr 14, 2026 09:58PM
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