Perhaps you should try some spelling variations:
learning environmental » learning environments, learning environment, planning environmental
operational conditions » operating conditions, operational considerations, operational definitions
varying environment » learning environment, making environment, marketing environment

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: ((varying environment) OR (learning environmental)) AND operational conditions.
• Adding a wildcard symbol may retrieve word variants: ((varying environment) or (learning environmental)) and operational conditions*.