Denis Naddef Najiba Sbihi Maurice Tchuenté Independence systems with continuous cardinality of bases. 107-109 1980 31 Discret. Math. 1 https://doi.org/10.1016/0012-365X(80)90181-8 https://www.wikidata.org/entity/Q126312789 db/journals/dm/dm31.html#NaddefST80