Perhaps you should try some spelling variations:
nonlinear properties » nonlinear processes, nuclear properties, nonlinear operators
nonlinear potential » nonlinear partial, nonlinear material
nonlinear spatial » nonlinear partial, nonlinear spectral, nonlinear static
spatial theory » special theory, social theory, spatial memory

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 potential) OR (nonlinear properties)) theory ) OR ( nonlinear spatial theory )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( ((nonlinear potential) OR (nonlinear properties)) theory ) or ( nonlinear spatial theory ))".
• Adding a wildcard symbol may retrieve word variants: (( ((nonlinear potential) OR (nonlinear properties)) theory ) or ( nonlinear spatial theory ))*.