Perhaps you should try some spelling variations:
practical astronomy » nautical astronomy, optical astronomy
guenon positional » non positional, gene positional, clemson positional
astronomy surveys » astronomy survey, astronomy surveying, astronomy survives
astronomy sergey » astronomy survey, astronomy seven, astronomy large
moore practical » more practical, moocs practical, mouse practical
patrick guenon » patrick glenn, patrick gordon, patrick green

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 moore practical astronomy sergey ) OR ( the patrick guenon positional astronomy surveys )).
• Adding a wildcard symbol may retrieve word variants: (( the patrick moore practical astronomy sergey ) or ( the patrick guenon positional astronomy surveys ))*.