Perhaps you should try some spelling variations:
practical astronomy » nautical astronomy
optical astronomy » nautical astronomy, spherical astronomy
astronomy sergey » astronomy survey, astronomy surveys, astronomy seven
pure positional » aware positional, pure conditional, pure rotational
meek practical » meets practical, risk practical, work practical
patrick pure » patrick burke, patrick part, patrick burk
patrick mkie » patrick mackie, patrick mein, patrick moore
mkie optical » moire optical, mode optical, more optical
patrick meek » patrick meier, patrick mein, 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 pure positional astronomy sergey ) OR ((( the patrick mkie optical astronomy sergey ) OR ( the patrick meek practical astronomy sergey )))).
• Adding a wildcard symbol may retrieve word variants: (( the patrick pure positional astronomy sergey ) or ((( the patrick mkie optical astronomy sergey ) or ( the patrick meek practical astronomy sergey ))))*.