Perhaps you should try some spelling variations:
practical astronomy » nautical astronomy, optical astronomy, positional astronomy
astronomy sergey » astronomy surveys, astronomy seven, astronomy large
astronomy survey » astronomy surveys, autonomy survey, astronomy surveying
moocs practical » books practical, mics practical, colts practical
patrick moocs » patrick moore, patrick mons, patrick moyes
patrick more » patrick moore, patrick moyes, patrick mkie

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 more practical astronomy survey )).
• Adding a wildcard symbol may retrieve word variants: (( the patrick moocs practical astronomy sergey ) or ( the patrick more practical astronomy survey ))*.