Perhaps you should try some spelling variations:
practical astronomy » nautical astronomy, optical astronomy, positional astronomy
astronomy surveying » astronomy during
astronomy survives » astronomy survey, astronomy surveys, astronomy studies
drops practical » does practical, drugs practical, aris practical
patrick drops » patrick debois, patrick dr, patrick brown
de optical » de optica, mode optical, edge optical
e optical » e optimal, mode optical, core 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 drops practical astronomy survives ) OR ( the patrick ((de optical) OR (e optical)) astronomy surveying )).
• Adding a wildcard symbol may retrieve word variants: (( the patrick drops practical astronomy survives ) or ( the patrick ((de optical) or (e optical)) astronomy surveying ))*.