@article {illert1987formulation,
	title = {Formulation and solution of the classical seashell problem},
	journal = {Il Nuovo Cimento D},
	volume = {9},
	number = {7},
	year = {1987},
	pages = {791{\textendash}814},
	publisher = {Springer},
	url = {http://www.vliz.be/imisdocs/publications/134361.pdf},
	author = {Illert, C.}
}
