W. K. Kwok, S. Fleshler, U. Welp, V. M. Vinokur, J. Downey, G. W. Crabtree, M. M. Miller,
Vortex lattice melting in untwinned and twinned single crystals of YBa 2 Cu 3 O 7 − δ Physical Review Letters. ,vol. 69, pp. 3370- 3373 ,(1992) ,
10.1103/PHYSREVLETT.69.3370