PHASE DIAGRAM OF A HEISENBERG HEXAGONAL LATTICE WITH IN-PLANE COMPETING INTERACTIONS: CLASSICAL AND QUANTUM SCENARIOS A. B. Harris, E. Rastelli et A. Tassi J. Phys. Colloques, 49 C8 (1988) C8-1395-C8-1396 DOI: 10.1051/jphyscol:19888640