Perhaps you should try some spelling variations:
practical astronomy » nautical astronomy, optical astronomy, positional astronomy
national astronomy » national autonomy, nautical astronomy, regional astronomy
astronomy sergey » astronomy survey, astronomy surveys, astronomy seven
moocs practical » books practical, mics practical, colts practical
moore national » moors national, more national, before national
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 moocs practical astronomy sergey ) OR ( the patrick moore national astronomy sergey )).
• Adding a wildcard symbol may retrieve word variants: (( the patrick moocs practical astronomy sergey ) or ( the patrick moore national astronomy sergey ))*.