1. J. App. Phys., 18, 988 (1947).
2. See, for example, Barr, "Monograph of Viscometry", 235 (Oxf. Univ. Press, 1931).
3. Indust. Eng. Chem., 34, 163 (1942).
4. Alfrey, "Mechanical Behavior of High Polymers", 39 (Interscience Publishers, 1948).
5. Nature, 149, 708 (1942).