Willett J. E., . (1991). Gas Chromatography : Analytical Chemistry By Open Learning. Weinheim: John Wiley.
Willett J E, . 1991. Gas Chromatography : Analytical Chemistry By Open Learning. Weinheim: John Wiley.
Willett J E, . Gas Chromatography : Analytical Chemistry By Open Learning. Weinheim: John Wiley. 1991.