Stonehenge: An Astronomical Calculator - Online Star Register
Practical Astronomy with Your Calculator or Spreadsheet by Jonathan Zwart and Peter Duffett-Smith (2011, Spiral, Revised edition) for sale online | eBay
What kind of calculator would a physicist with a PhD use? - Quora
bookofjoe: CalSky — 'The most complete astronomical observation and information online-calculator on the planet'
StarDate Online | Your guide to the universe
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