G. Parlagh, G. Székely, and G. Rácz, “MATHEMATICAL SIMULATION OF CONTINUNOUS GAS CHROMATOGRAPHY I. A SET OF GENERAL DIFFERENTIAL EQUATIONS DESCRIBING THE BEHAVIOUR OF A CONTINUOUS CHROMATOGRAPHIC COLUMN”, Period. Polytech. Chem. Eng., vol. 20, no. 3, pp. 205–221, Jan. 1976.