@article{AM2_1968__1_135938,
     author = {H. Haruki and J. Acz\'el and M.A. McKiernan},
     title = {General and {Regular} {Solutions} of {Functional} {Equations} {Characterizing} {Harmonic} {Polynomials.}},
     journal = {Aequationes mathematicae},
     pages = {37--53},
     publisher = {mathdoc},
     volume = {1},
     year = {1968},
     zbl = {0157.46102},
     url = {http://geodesic.mathdoc.fr/item/AM2_1968__1_135938/}
}