@第{zbMATH05608115条，作者＝{Al-Banawi，Kamal}，标题={{（\mathbb R^4\）}}}中4-超正态圆环的焦点，FJournal={格鲁吉亚数学杂志}，期刊={格鲁吉亚数学杂志}，ISSN={1072-947X}，体积={16}，数字={2}，Pages={211-218}，年份={2009}，语言={英语}，关键词={53A07}，URL={www.heldermann.de/GMJ/GMJ16/GMJ162/gmj16015.htm}，zbMATH={5608115}，Zbl={1173.53301}}