@article{GDZPPN002477106, title = {Idempotency of Circuit-induced Exchange Operators.}, journal = {Monatshefte f\"ur Mathematik}, volume = {74}, year = {1970}, pages = {330-335}, zbl = {0239.05130}, url = {http://dml.mathdoc.fr/item/GDZPPN002477106} }
Sabidussi, Gert. Idempotency of Circuit-induced Exchange Operators.. Monatshefte für Mathematik, Tome 74 (1970) pp. 330-335. http://gdmltest.u-ga.fr/item/GDZPPN002477106/