Here are entered works on foreign-born persons who enter a country intending to become permanent residents or citizens. Works on persons who change their place of residence from one locality to another within the borders of a single country are entered under Internal migrants.This heading may be locally subdivided by names of places where immigrants settle.For works discussing emigrants from a particular place, an additional heading is assigned to designate the nationality of origin of the emigrant group and the place to which they have immigrated, e.g. Chinese--United States; Americans--Foreign countries.
Here are entered works on trade among nations. Works on foreign trade of specific countries, cities, etc. are entered under headings of the type [place]--Commerce, further subdivided by place, if appropriate. If so subdivided, a second heading is assigned with the place names in reverse positions, e.g. 1. Canada--Commerce--United States. 2. United States--Commerce--Canada.