@article{GDZPPN002076411, title = {Area of the Union of Disks.}, journal = {Elemente der Mathematik}, volume = {23}, year = {1968}, pages = {60-63}, url = {http://dml.mathdoc.fr/item/GDZPPN002076411} }
Spilker, J.; Richter, M.W. Area of the Union of Disks.. Elemente der Mathematik, Tome 23 (1968) pp. 60-63. http://gdmltest.u-ga.fr/item/GDZPPN002076411/