1. Struik LCE (1978) Physical aging in amorphous polymers and other materials. Elsevier Scientific Publishing Company, New York
2. Traxler RN, Schweyer HE (1936) Increase in viscosity of asphalts with time. Proc Am Soc Test Mater 36(2):544–550
3. Traxler RN, Coombs CE (1937) Development of internal structure in asphalts with time. Proc Am Soc Test Mater 37(2):549–557
4. Nellensteyn F (1924) The constitution of asphalt. J Inst Pet Technol 10:311–323
5. Brown AB, Sparks JW, Smith FM (1957) Steric hardening of asphalts. Proc Assoc Asphalt Paving Technol 26:486–494