ROBERTS, J. A. G. (1998). Modern China. An illustrated history. Sutton Publishing, Somerset, p. 75

Memorial de Li Hongzhang, 1872, reclamant la necessitat d'obrir mines i crear transports per consolidar els arsenals existents.

Furthermore, the building of ships, cannon, and machinery will be impossible without iron, and then we shall be helpless without coal. The reason for England's power and influence over the Western lands is only her possession of these two items [iron and coal]. The various arsenals in Fuzhou and Shanghai daily need a huge amount of imported coal and fron, because the Chinese product is most unsuitable.