…the ultimate determining element in the employment of shipping lies in the sum of geographical conditions of each region in relation to other regions of the world, though the effect of such conditions may be modified greatly by economic or political policy on the part of individuals or government.Sargent (1930) apud Lun, Lai e Cheng (2010)
LUN, Y. H. V.; LAI, K. -h.; CHENG, T.c.e.. Shipping and Logistics Management. Londres: Springer-verlag, 2010. 243 p.