Perhaps you should try some spelling variations:
"classical mechanisms" » "classical mechanism", "classical mechanistic", "classical mechanical"
"physical mechanism" » "physical mechanisms", "physical mechanical", "chemical mechanisms"
"classical mechanics" » "classical mechanical"

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: (("classical mechanics") OR ((("classical mechanisms") OR ("physical mechanism")))).
• Removing quotes may allow a broader search: (( classical mechanics ) or ((( classical mechanisms ) or ( physical mechanism )))).
• Adding a wildcard symbol may retrieve word variants: (("classical mechanics") or ((("classical mechanisms") or ("physical mechanism"))))*.