Explanation of multiplet spots in low-energy electron diffraction patterns of clean GaN{0001}-1x1 surfaces O. Janzen, Ch. Hahn, T. U. Kampen and W. Mönch Eur. Phys. J. B, 7 1 (1999) 1-4 Published online: 15 January 1999 DOI: 10.1007/s100510050583