Books are shelved in general subject categories using the Library of Congress classification system. You may want to supplement your use of the catalog book search with browsing shelf areas for your topic.
If you are interested in browsing for books on your subject, you might look in the following areas.
E 184 - E 185.98 ---- Elements in the population
JV 6201 - JV 7127 ---- Emigration and immigration. International migration
Materials not available at Gustavus might be borrowed from other libraries and sent here for you to use.
from Oviatt Library at California State University, Northridge: http://library.csun.edu/ResearchAssistance/LCC