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

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 conditions") OR ("varying environment 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 conditions\") OR (\"varying environment and operational conditions\"))) or (\"varying environments and operational considerations\"))*".
• Removing quotes may allow a broader search: (((( varying environments and operational conditions ) OR ( varying environment and operational conditions ))) or ( varying environments and operational considerations ))*.