Perhaps you should try some spelling variations:
optical astronomy » spherical astronomy, positional astronomy
astronomy sergey » astronomy surveys, astronomy seven, astronomy large
astronomy survey » astronomy surveys, autonomy survey, astronomy surveying
moore nautical » board nautical, mile nautical, moore national
patrick moocs » patrick mons, patrick moyes, patrick moore's
moocs optical » moon optical, topics optical, loss optical

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