Get you own copy of the pdb file used here.
Albright, Ronald A. and Brian W. Mathews. How Cro and Lambda-repressor Distinquish Between Operators: The Structural Basis Underlying a Genetic Switch. Proc. Natl. Acad. Sci. (1998) 95:3431-3436 [link]
Beamer, Lesa J. and Carl O. Pabo. Refined 1.8A Crystal Structure of the Lambda Repressor-Operator Complex. J.Mol.Biol. (1992) 227:177-198 [link]
Benson, Nicholas and Philip Youderian. Phage lambda Cro Protein and cI Repressor Use Two Different Patterns of Specific Protien-DNA Interactions to Acheive Sequence Specificity in Vivo. Genomics (1989) 121:5-12
Kim, Yong-In and James C. Hu. Operator Binding by Lambda Repressor Heterodimers with One or Two N-terminal Arms. Proc. Natl. Acad. Sci. (1995) 92:7510-7514 [link]
Li, Mei, W.R. McClure and Miriam M. Susskind. Changing the Mechanism of Transcriptional Activation by Phage Lambda Repressor. Proc. Natl. Acad. Sci. (1997) 94:3691-3696 [link]
A special thanks to Dr. Jon Scales at UWEC...whos teaching of the operator system and generous donation of figures in the introduction have made this paper the masterpeice it was intended to become.