商務文件包括1927－1954 年間商業夥伴、供應商、代理商和客戶寄來的大量信件，合計 2,350 多張，有些用繩子裝訂成冊，有些寫在袖珍本子裡，更有寫在白棉布上，這類帛書共有 40 張，是 1939－1941 年間西貢新公生隨貨運寄來的。帶信頭的信紙皆為商務信，其餘歸入私人信件內，共有 221 張。除信件外，還有1937、1940及1941年致怡興隆的電報，共175張。 文檔還包括怡興隆在1939－1941、1946、1947和 1951 年致各商號的信稿、留底信和電報。此外還有各號的貨價單、通告和啟事等，主要是 1930 年代的文件。

This subseries contains a large quantity of letters spanning from 1927 to 1954. They are from business partners, suppliers, agents and clients amounting to more than 2,350 sheets. Some were string-bound and some in pocket-sized notebooks. Unlike letters usually written on paper, there are business letters written on white cotton cloth, 40 pieces in total, dated between 1939 and 1941 from Tân-CÔng-Sanh, a business partner in Saigon. Letters not using headed paper are now grouped with other personal letters making a total of 221 sheets. Besides letters, there are 175 telegrams sent to Yee Hing Loong in 1937, 1940 and 1941. Under this subseries are draft or record copy of letters and telegrams sent from Yee Hing Loong to business partners in 1939-1941, 1946, 1947 and 1951. Also contained herein are notices, price list etc. mostly in the 1930s.