Dandan Li Liping Yuan Tudor Zamfirescu Right quadruple convexity. 25-38 2018 14 Ars Math. Contemp. 1 https://doi.org/10.26493/1855-3974.1022.a6a https://www.wikidata.org/entity/Q129389239 db/journals/arsmc/arsmc14.html#LiYZ18