Advantages of the pseudopressure concept to incorporate second-degree terms. The circles, squares and diamonds are the Cole-Hopf solutions (dashed lines) when expressed in terms of pseudopressures. Alignment with the classical finite-well-radius solution shown as a unbroken line is excellent. Norms based on the concept of a slightly-compressible fluid apply when pressures are evaluated through the pseudopressure concept or Kirchhoff transformation.