CSICSAY, K., M. BIELIK, A. MOJZEŠ, E. SPEVÁKOVÁ, B. KYTKOVÁ, and M. GRINČ. “Linearization of the Sobolev and Babeyko’s Formulae for Transformation of P-Wave Velocity to Density in the Carpathian-Pannonian Basin Region”. Contributions to Geophysics and Geodesy, Vol. 42, no. 1, Mar. 2012, pp. 15-23, doi:10.2478/v10126-012-0002-y.