Radziszewski, Piotr, Robert Ziolkowski, and Donatas Čygas. “Technological Ageing Influence on Viscosity of Selected Bitumens”. Journal of Civil Engineering and Management 9, no. 1 (March 31, 2003): 20-24. Accessed November 15, 2019. https://journals.vgtu.lt/index.php/JCEM/article/view/9010.