Perhaps you should try some spelling variations:
"varying environments and operational considerations" » "varying environments and computational considerations", "varying environments and additional considerations", "varying environment and operational considerations", "working environments and operational considerations", "changing environments and operational considerations"
"varying environments and operational definitions" » "varying environments and operational definition", "varying environments and operational decision", "varying environment and operational definitions", "working environments and operational definitions", "changing environments and operational definitions"
"varying environments and operational conditions" » "varying environments and operating conditions", "varying environments and operational control", "varying environment and operational conditions", "working environments and operational conditions", "changing environments and operational conditions"
"learning environments and operational conditions" » "learning environments and operating conditions", "learning environments and operational control"

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: (("varying environments and operational definitions") OR ((((("varying environments and operational conditions") OR ("learning environments and operational conditions"))) OR ("varying environments and operational considerations")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"varying environments and operational definitions\") or (((((\"varying environments and operational conditions\") OR (\"learning environments and operational conditions\"))) or (\"varying environments and operational considerations\"))))".
• Removing quotes may allow a broader search: (( varying environments and operational definitions ) or ((((( varying environments and operational conditions ) OR ( learning environments and operational conditions ))) or ( varying environments and operational considerations )))).
• Adding a wildcard symbol may retrieve word variants: (("varying environments and operational definitions") or ((((("varying environments and operational conditions") OR ("learning environments and operational conditions"))) or ("varying environments and operational considerations"))))*.