@article{MS2_1976__39_166498,
     author = {A.F. Horadam and A.G. Shannon},
     title = {Ward's {Staut-Clausen} problem.},
     journal = {Mathematica Scandinavica},
     pages = {239--250},
     publisher = {mathdoc},
     volume = {39},
     year = {1976},
     zbl = {0347.10010},
     url = {http://geodesic.mathdoc.fr/item/MS2_1976__39_166498/}
}