Perhaps you should try some spelling variations:
production learning » prediction learning, reduction learning, productive learning
projection learning » projects learning, prediction learning, propagation learning
22adult learning » adult learning, adults learning, adt learning
product planning » project planning, production planning
project learning » project planning, project defining

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: %((22adult learning) OR (((((((production learning) OR (projection learning))) OR (product planning))) OR (project learning))))%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%((22adult learning) or (((((((production learning) OR (projection learning))) or (product planning))) or (project learning))))%22".
• Adding a wildcard symbol may retrieve word variants: %((22adult learning) or (((((((production learning) OR (projection learning))) or (product planning))) or (project learning))))%22*.