Pseudogap and order-parameter symmetry in the underdoped high-Tc compounds and : A neutron crystal-field studyJ. Mesot, G. Böttger, H. Mutka and A. FurrerEurophys. Lett., 44 4 (1998) 498-503DOI: https://doi.org/10.1209/epl/i1998-00501-8