Cosmological aspects of sound speed parameterizations in fractal universe Abdul Jawad, Sadaf Butt, Shamaila Rani and Khadija Asif Eur. Phys. J. C, 79 11 (2019) 926 Published online: 14 November 2019 DOI: 10.1140/epjc/s10052-019-7445-5