Schroeder, L A.(2007). The -11A of promoter DNA and two conserved amino acids in the melting region of  70 both directly affect the rate limiting step in formation of the stable RNA polymerase-promoter complex, but they do not necessarily interact. Nucleic Acids Research, 35(12), 4141-4153. doi:10.1093/nar/gkm431

Schroeder, L. A. "The -11A of Promoter DNA and Two Conserved Amino Acids in the Melting Region of  70 Both Directly Affect the Rate Limiting Step in Formation of the Stable RNA Polymerase-promoter Complex, but They Do Not Necessarily Interact". Nucleic Acids Research, 35.12 ( 2007 ): 4141-4153.