Perhaps you should try some spelling variations:
practical astronomy » optical astronomy
astronomy sergey » astronomy survey, astronomy surveys, astronomy seven
modes positional » model depositional, modem depositional, images positional
modes practical » models practical, model practical, codes practical
moore practical » more practical, moocs practical, mouse practical
moocs nautical » moocs practical, hoc nautical, logs nautical
patrick modes » patrick moyes, patrick mons, trick modes
patrick moocs » patrick mons, patrick moyes, patrick moore's

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 modes practical astronomy sergey ) OR ( the patrick modes positional astronomy sergey ))) OR ( the patrick moore practical astronomy sergey ))) OR ( the patrick moocs nautical astronomy sergey )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(((((( the patrick modes practical astronomy sergey ) OR ( the patrick modes positional astronomy sergey ))) or ( the patrick moore practical astronomy sergey ))) or ( the patrick moocs nautical astronomy sergey ))".
• Adding a wildcard symbol may retrieve word variants: (((((( the patrick modes practical astronomy sergey ) OR ( the patrick modes positional astronomy sergey ))) or ( the patrick moore practical astronomy sergey ))) or ( the patrick moocs nautical astronomy sergey ))*.