@article{AM2_1992__44_1_137489,
     author = {R. Padmanabhan and P. Penner},
     title = {Binary hyperidentities.},
     journal = {Aequationes mathematicae},
     pages = {154--167},
     year = {1992},
     volume = {44},
     number = {1},
     url = {http://geodesic.mathdoc.fr/item/AM2_1992__44_1_137489/}
}