Perhaps you should try some spelling variations:
nonlinear properties » nonlinear processes, nuclear properties, nonlinear operators
properties theory » properties other, property theory, properties thermal
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 properties theory ) OR ( nonlinear spatial theory ))*.