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 surveys, astronomy seven, astronomy large
astronomy survey » astronomy surveys, autonomy survey, astronomy surveying
moocs practical » mics practical, abcs practical, ics practical
mons practical » coins practical, lens practical, loss practical
moore national » moors national, more national, before national
patrick moocs » patrick moyes, patrick moore's
patrick mons » patrick moyes, patrick bond, patrick mpondo

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