Perhaps you should try some spelling variations:
"classical mechanical" » "classical mechanics", "statistical mechanical", "classical mathematical"
"chemical mechanical" » "chemical mechanisms", "thermal mechanical", "chemo mechanical"
"physical mechanical" » "physico mechanical", "physical mechanisms"
"classical mechanism" » "classical mechanisms", "classical mechanics", "classical mechanistic"

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 mechanical") OR ("chemical mechanical"))) OR ("physical mechanical"))) OR ("classical mechanism")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((((\"classical mechanical\") OR (\"chemical mechanical\"))) or (\"physical mechanical\"))) or (\"classical mechanism\"))".
• Removing quotes may allow a broader search: (((((( classical mechanical ) OR ( chemical mechanical ))) or ( physical mechanical ))) or ( classical mechanism )).
• Adding a wildcard symbol may retrieve word variants: (((((("classical mechanical") OR ("chemical mechanical"))) or ("physical mechanical"))) or ("classical mechanism"))*.