Perhaps you should try some spelling variations:
22language acquisition » language acquistion, interlanguage acquisition
bilingual acquisition » biosignal acquisition, signal acquisition, digital acquisition
langage acquisition » language acquistion, image acquisition, land acquisition

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