Perhaps you should try some spelling variations:
"nonlinear particles theory" » "collinear particles theory", "nonlinear partial theory", "nonlinear vortices theory", "nonlinear partials theory", "collinear particless theory", "linear particles theory", "nonlinear particles through"
"nonlinear particle theory" » "nonlinear partial theory", "collinear particles theory", "linear particle theory"
"nonlinear material theory" » "nonlinear materials theory", "nonlinear matrix theory", "nonlinear partial theory"

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: (((("nonlinear particle theory") OR ("nonlinear particles theory"))) OR ("nonlinear material theory")).
• Removing quotes may allow a broader search: (((( nonlinear particle theory ) or ( nonlinear particles theory ))) or ( nonlinear material theory )).
• Adding a wildcard symbol may retrieve word variants: (((("nonlinear particle theory") or ("nonlinear particles theory"))) or ("nonlinear material theory"))*.