A four-constant model for viscoelastic fluids 

 -  Chemical Engineering Science, 20(11), p.931-940, 1965 .
<br/><br/> A nonlinear extension of the generalized Maxwell model is proposed as a constitutive equation for viscoelastic fluids. Expressions for complex-viscosity, oscillatory normal stresses, non-Newtonian viscosity and two normal stress differences are given in terms of four parameters. Comparison is made with M. C. Williams' complex-viscosity data for 1·46