  Hydrodynamic self-similar solutions, as obtained by Chi [J. Math. Phys. 24,
2532 (1983)] have been generalized by introducing new variables in place of the
old space and time variables. A systematic procedure of obtaining a complete
set of solutions has been suggested. The Newtonian analogs of all homogeneous
isotropic Friedmann dust universes with spatial curvature $k = 0, \pm 1$ have
been given.
