Ibrahim, A., & Ibrahim Abdullah. The deevelopment potential of the Sabang Freeport and Free Trade Zone. (1972). The Sabang freeport and the free trade zone as institutional means in performing the tasks of public and co-operative economy. Savang Free Trade Zone and Freeport.

Ibrahim, Abdullah, and Ibrahim Abdullah. The deevelopment potential of the Sabang Freeport and Free Trade Zone. The Sabang Freeport and the Free Trade Zone as Institutional Means in Performing the Tasks of Public and Co-operative Economy. [Sabang]: Savang Free Trade Zone and Freeport, 1972.

Ibrahim, Abdullah, and Ibrahim Abdullah. The deevelopment potential of the Sabang Freeport and Free Trade Zone. The Sabang Freeport and the Free Trade Zone as Institutional Means in Performing the Tasks of Public and Co-operative Economy. Savang Free Trade Zone and Freeport, 1972.