1. D.B. Broughton, C.G. Gerhold, Continuous sorption process employing fixed bed of sorbent and moving inlets and outlets, US Patent 2,985,589 (1961).
2. Countercurrent and simulated countercurrent adsorption separation processes;Ruthven;Chem. Eng. Sci.,1989
3. Robust design of binary countercurrent adsorption separation processes;Storti;AIChE J.,1993
4. The “VARICOL” process: a new multicolumn continuous chromatographic process;Ludemann-Hombourger;Sep. Sci. Technol.,2000
5. P. Adam, R.M. Nicoud, M. Bailly, O. Ludemann-Hombourger, Process and device for separation with variable-length, US Patent 6,136,198, (2000).