  We present the exact solution of a family of two-spins models. The models are
solved by the algebraic Bethe ansatz method using the $gl(2)$-invariant
$R$-matrix and a multi-spins Lax operator. The interactions are by the
Heisenberg spins exchange. We are also considering magnetic $B$-fields and a
term for Haldane single spin anisotropy.
