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
1207 members — last activity 9 hours, 24 min ago
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Goodreads Authors/Readers
57105 members — last activity 8 hours, 40 min ago
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The Evolution of Science Fiction
1917 members — last activity Jul 09, 2026 09:21PM
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Sci-fi and Heroic Fantasy
8897 members — last activity 9 hours, 20 min ago
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Science and Inquiry
4528 members — last activity Jul 10, 2026 11:50PM
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Science and Natural History
1137 members — last activity Sep 22, 2020 01:21PM
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Astronomy and Space exploration
299 members — last activity Jun 24, 2026 07:00AM
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