Perhaps you should try some spelling variations:
"collinear particles theory" » "collider particle theory", "colloidal particles theory", "colliding particles theory", "collinear particles through"
"nonlinear particle theory" » "linear particle theory", "nonlinear price theory", "nuclear particle theory"
"nonlinear material theory" » "nonlinear matrix theory", "nonlinear media theory", "nonlinear water theory"
"nonlinear materials theory" » "nonlinear matrixs theory", "nonlinear medias theory", "nonlinear waters theory"
"nonlinear partial theory" » "nonlinear spatial theory", "nonlinear partial memory", "nonlinear partial tears"

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 partial theory") OR ((("nonlinear particle theory") OR ("collinear particles theory"))))) OR ((("nonlinear material theory") OR ("nonlinear materials theory")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"nonlinear partial theory\") or (((\"nonlinear particle theory\") or (\"collinear particles theory\"))))) or (((\"nonlinear material theory\") OR (\"nonlinear materials theory\"))))".
• Removing quotes may allow a broader search: (((( nonlinear partial theory ) or ((( nonlinear particle theory ) or ( collinear particles theory ))))) or ((( nonlinear material theory ) OR ( nonlinear materials theory )))).
• Adding a wildcard symbol may retrieve word variants: (((("nonlinear partial theory") or ((("nonlinear particle theory") or ("collinear particles theory"))))) or ((("nonlinear material theory") OR ("nonlinear materials theory"))))*.