End-Chain Spin Effects in Haldane Gap Materials
  This 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). 
Mark W. Meisel (Department of Physics, University of Florida,   Gainesville)