Perhaps you should try some spelling variations:
"Critical issues in environmental evaluation" » "Critical issues in environmental education", "Critical issues in environmental regulation", "Critical issues in environmental degradation"
"critical issues in environmental radiation" » "critical issues in environmental remediation", "critical issues in environmental degradation", "critical issues in environmental regulation", "practical issues in environmental radiation"

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: (("Critical issues in environmental evaluation") OR ("critical issues in environmental radiation")).
• Removing quotes may allow a broader search: (( Critical issues in environmental evaluation ) or ( critical issues in environmental radiation )).
• Adding a wildcard symbol may retrieve word variants: (("Critical issues in environmental evaluation") or ("critical issues in environmental radiation"))*.