Columbia subject headings:
Developing countries--Vaccination--Congresses.
Vaccination--Africa--Congresses.
Vaccination--International cooperation--Congresses.
Harvard subject headings:
Vaccination--Africa--Congresses.
Vaccination--Developing countries--Congresses.
Vaccination--International cooperation--Congresses.
Princeton subject headings:
Vaccination--Africa--Congresses.
Vaccination--Developing countries--Congresses.
Vaccination--International cooperation--Congresses.