Keim, P. Max Planck Institute for Dynamics and Self-Organization, Max Planck Society;
Link (beliebiger Volltext)
Keim, P., Maret, G., & von Grünberg, H. H. (2007). Frank's constant in the hexatic phase. Physical Review E, 75(3): 031402. doi:10.1103/Physreve.75.031402.