@article{GDZPPN002082721,
title = {On permutations involving pairs of twins.},
journal = {Elemente der Mathematik},
volume = {46},
year = {1991},
pages = {78-83},
zbl = {0758.05002},
url = {http://dml.mathdoc.fr/item/GDZPPN002082721}
}
Kuczma, Marcin E. On permutations involving pairs of twins.. Elemente der Mathematik, Tome 46 (1991) pp. 78-83. http://gdmltest.u-ga.fr/item/GDZPPN002082721/