1
Galileo and 400 Years of Telescopic Astronomy [E-Book] /
Other Personal Name(s): ...Grego, Peter....

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2
Astronomical Cybersketching [E-Book] : Observational Drawing with PDAs and Tablet PCs /
3
Venus and Mercury, and how to observe them / [E-Book]
Other Personal Name(s): ...Grego, Peter....

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