Perhaps you should try some spelling variations:
nonlinear particles » collinear particles, nonlinear partial, nonlinear martingales
nonlinear vortices » nonlinear optics, nonlinear lattices, nonlinear forces
nonlinear material » nonlinear materials, nonlinear matrix, nonlinear partial
material theory » materials theory
partial theory » particle theory, particles theory, partial tears
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 ((partial theory) OR (spatial theory)) ) OR ( ((nonlinear particles) OR (nonlinear vortices)) theory ))) OR ( nonlinear material theory )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(((( nonlinear ((partial theory) or (spatial theory)) ) or ( ((nonlinear particles) OR (nonlinear vortices)) theory ))) or ( nonlinear material theory ))".
• Adding a wildcard symbol may retrieve word variants: (((( nonlinear ((partial theory) or (spatial theory)) ) or ( ((nonlinear particles) OR (nonlinear vortices)) theory ))) or ( nonlinear material theory ))*.