@article{01549917,
title = {Isoptics of pairs of nested closed strictly convex curves and Crofton-type formulas.},
journal = {Beitr\"age zur Algebra und Geometrie},
volume = {42},
year = {2001},
pages = {281-288},
zbl = {1021.53050},
language = {en},
url = {http://dml.mathdoc.fr/item/01549917}
}
Miernowski, A.; Mozgawa, W. Isoptics of pairs of nested closed strictly convex curves and Crofton-type formulas.. Beiträge zur Algebra und Geometrie, Tome 42 (2001) pp. 281-288. http://gdmltest.u-ga.fr/item/01549917/