Perhaps you should try some spelling variations:
practical astronomy » nautical astronomy, positional astronomy
optical astronomy » nautical astronomy, spherical astronomy, positional astronomy
astronomy sergey » astronomy survey, astronomy surveys, astronomy large
astronomy seven » astronomy some, astronomy science, astronomy between
moore optical » moire optical, more optical, core optical
patrick more » patrick moyes, patrick mkie, patrick mark

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (( the patrick moore optical astronomy sergey ) OR ( the patrick more practical astronomy seven )).
• Adding a wildcard symbol may retrieve word variants: (( the patrick moore optical astronomy sergey ) or ( the patrick more practical astronomy seven ))*.