Perhaps you should try some spelling variations:
optical astronomy » nautical astronomy, spherical astronomy
astronomy sergey » astronomy survey, astronomy surveys, astronomy seven
pure positional » aware positional, pure conditional, pure rotational
patrick pure » patrick burke, patrick part, patrick burk
patrick more » patrick moore, patrick moyes, patrick mkie
more optical » moire optical, mode optical, core optical

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 more optical astronomy sergey )).
• Adding a wildcard symbol may retrieve word variants: (( the patrick pure positional astronomy sergey ) or ( the patrick more optical astronomy sergey ))*.