EXCITATION SPECTRUM OF ANTIFERROMAGNETIC RINGS
PHYSICAL REVIEW 171:2 (1968) 572-+
ALTERNANT SPIN WAVES IN HEISENBERG ANTIFERROMAGNET
MOLECULAR PHYSICS 12:4 (1967) 319-+
SYMMETRY PROPERTIES OF EXCITON STATES IN 1 DIMENSIONAL SYSTEMS
MOLECULAR PHYSICS 12:4 (1967) 301-+