2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/28581This paper overviews the behavior of the end-chain spins of linear chain systems possessing a Haldane gap. The physical properties of the end-chain spins are described by reviewing the results obtained primarily with materials known as NENP, Ni(C2H8N2)2NO2(ClO4), and NINAZ, Ni(C3H10N2)2N3(ClO4).4 pages, 3 figures, Invited paper at the 10th Czech and Slovak Conference on Magnetism, Kosice, Slovakia, 24-27 August 1998, to be published in Acta Physica Slovaca (probably in December 1998)Condensed Mattertext