Perhaps you should try some spelling variations:
astronomy series » astronomy sergey, gastronomy services, astronomy survives
moore practical » more practical, mouse practical, course practical
moocs practical » mics practical, does practical, drops practical

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