. "op art" . "Op art" . . . "optrickery" . . "Op Art." . . . . . "Op art#The Responsive Eye" . . "\\\"the Responsive Eye\\\"" . . "optical art" . . . "Opt Art" . "Op-Art" . . . . . . . "optical artists" . "op" . . . . "optical" . . "Op art movement" . . . . . "op-art" . . . . "'''Op Art'''" . . "Op art or optical art" . . . . . . . . "Op Art\u201D" . "Op" . . . . . . "Op art" . "Op Art" . . "optical artwork" . . .