Quantum rotations in natural methane-clathrates from the Pacific sea-floor C. Gutt, B. Asmussen, W. Press, C. Merkl, H. Casalta, J. Greinert, G. Bohrmann, J. S. Tse and A. Hüller Europhys. Lett., 48 3 (1999) 269-275 Published online: 01 September 2002 DOI: 10.1209/epl/i1999-00476-x