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

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