Perhaps you should try some spelling variations:
planning acquisition » reading acquisition, imaging acquisition, thinking acquisition
language acquistion » language question, language action, language attrition
langage acquisition » land acquisition

Try widening your search to All Fields.

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: %((language acquisition) OR (((language acquistion) OR (((((langage acquisition) OR (image acquisition))) OR (planning acquisition)))))) AND development%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%((language acquisition) or (((language acquistion) or (((((langage acquisition) OR (image acquisition))) or (planning acquisition)))))) and development%22".
• Adding a wildcard symbol may retrieve word variants: %((language acquisition) or (((language acquistion) or (((((langage acquisition) OR (image acquisition))) or (planning acquisition)))))) and development%22*.