@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/