1. R. Darakchiev, DSc Thesis, Technical University, Sofia, Bulgaria, 1989.
2. X. Yuan, W. Li, The influence of various gas inlets on gas distribution in packed columns, Institution of Chemical Engineers Symposium Series No. 142, part 2, (1997) 931–938.
3. Ph. Suess, Analysis of gas entries of packed columns for two phase flow, Institution of Chemical Engineers Symposium Series No. 128 (1992) A369–A383.
4. Low pressure drop gas distributors for packed distillation columns;Muir;Can. J. Chem. Eng.,1986
5. Gas flow distributor for packed bed columns;Dodev;Bulg. Chem. Commun.,1999