Mark Yashar's Profile > Mark's Groups

Fans of Arthur C. Clarke
103 members — last activity Jun 01, 2019 11:56AM
Mark's comments (1)

Hard SF
1211 members — last activity Jul 27, 2026 09:48AM
Mark's comments (1)

Goodreads Authors/Readers
57489 members — last activity 3 hours, 47 min ago
Mark's comments (0)

The Evolution of Science Fiction
1943 members — last activity 11 hours, 45 min ago
Mark's comments (0)

Sci-fi and Heroic Fantasy
8952 members — last activity 6 hours, 26 min ago
Mark's comments (0)

Science and Inquiry
4537 members — last activity 11 hours, 49 min ago
Mark's comments (0)

Science and Natural History
1137 members — last activity Sep 22, 2020 01:21PM
Mark's comments (0)

Astronomy and Space exploration
302 members — last activity Jun 24, 2026 07:00AM
Mark's comments (0)