2020-07-29T10:48:31.4800000Z
https://www.termdat.bk.admin.ch/entry/133770
Languages Act, art. 15 para. 3 (SR 441.1, transl., status 2017-01)
DFI, Quadrilinguismo svizzero, 1989, pag. 9
DFI, Quadrilinguisme en Suisse, 1989, p. 7
EDI, Viersprachige Schweiz, 1989, S. 102 f.