Description:Content: Bond length-bond valence relationships, with particular reference to polyoxometalate chemistry / K.H. Tytko -- A bond model for polyoxometalate ions composed of MO6 octahedra (MOk polyhedraa with k > 4) / K.H. Tytko -- Bonding and charge distribution in isopolyoxometalate ions and relevant oxides -- a bond valence approach / K.H. Tytko