Hettmann, T, Siddiqui RA, van Langen J, Frey C, Romao MJ, Diekmann S.  2003.  Mutagenesis study on the role of a lysine residue highly conserved in formate dehydrogenases and periplasmic nitrate reductases. Biochemical and Biophysical Research Communications. 310:40-47., Number 1