Columbia subject headings:
Emigration and immigration--Political aspects.
Mobile communication systems--Political aspects.
Mobile communication systems--Social aspects.
Harvard subject headings:
Emigration and immigration
Emigration and immigration--Political aspects
Mobile communication systems--Political aspects.
Mobile communication systems--Social aspects.
Princeton subject headings:
Emigration and immigration--Political aspects.
Emigration and immigration.
Mobile communication systems--Political aspects.
Mobile communication systems--Social aspects.