Perhaps you should try some spelling variations:
practical astronomy » optical astronomy, positional astronomy
astronomy sergey » astronomy survey, astronomy surveys, astronomy seven
drops practical » aris practical, devops practices, arrays practical
moocs nautical » moocs practical, hoc nautical, logs nautical
patrick drops » patrick debois, patrick dr, patrick brown
patrick moocs » patrick moore, patrick mons, patrick moyes

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