Perhaps you should try some spelling variations:
introduction comprehension » introduction comprehensive, information comprehension, instruction comprehensive
programming errors » programming reactors, programming entropy, programming factors
programming effort » programming effects, programming expert, programming sport
concept care » concepts care, concept car, concept card

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: introduction comprehension ((programming errors) or (programming effort)) concept care~.
• If you are trying to use Boolean operators, they must be ALL CAPS: introduction comprehension ((programming errors) OR (programming effort)) concept care.
• Adding a wildcard symbol may retrieve word variants: introduction comprehension ((programming errors) or (programming effort)) concept care*.