Fechtenkötter, A., Saalwächter, K., Harbison, M. A., Müllen, K., & Spiess, H. W. (1999). Highly Ordered Columnar Structures from Hexa-peri-hexabenzocoronene - Synthesis, X-ray Diffraction, and Solid-State Heteronuclear Multiple-Quantum NMR Investigations. Angewandte Chemie-International Edition, 38, 3039-3042.