Heckl, W. M., Smith, D. P., Binnig, G., Klagges, H., Hänsch, T. W., & Maddocks, J. (1991). Two-dimensional ordering of the DNA base guanine observed by scanning tunneling microscopy. Proc Natl Acad Sci U S A.

Heckl, W M., D P. Smith, G. Binnig, H. Klagges, T W. Hänsch, and J. Maddocks. "Two-dimensional Ordering of the DNA Base Guanine Observed By Scanning Tunneling Microscopy." Proc Natl Acad Sci U S A 1991.

Heckl, W M., et al. "Two-dimensional Ordering of the DNA Base Guanine Observed By Scanning Tunneling Microscopy." Proc Natl Acad Sci U S A 1991.