Perhaps you should try some spelling variations:
bilingual acquisition » biosignal acquisition, signal acquisition, digital acquisition
language attrition » language detection, language cognition, language action
language question » language education, language detection

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: %((bilingual acquisition) OR (((((language attrition) OR (language question))) OR (language acquisition)))) AND development%22.
• Adding a wildcard symbol may retrieve word variants: %((bilingual acquisition) or (((((language attrition) or (language question))) or (language acquisition)))) and development%22*.