FeatureGems & Gemology, Fall 1991, Vol. 27, No. 3越南红宝石与彩色蓝宝石 (英语)Robert E. Kane, Shane F. McClure(谢恩·F.·麦克卢尔), Robert C. Kammerling, Nguyen Dang Khoa, Carlo Mora, Saverio Repetto, Nguyen Duc Khai, John I. Koivula(约翰· I.·科伊武拉)下载 PDF 版本