Columbia subject headings:
Environmental engineers--Costa Rica--Directories.
Environmental protection--Costa Rica--Handbooks, manuals, etc.
Environmental sciences--Costa Rica--Societies, etc.--Directories.
Harvard subject headings:
Environmental engineers--Costa Rica--Directories.
Environmental protection--Costa Rica--Handbooks, manuals, etc.
Environmental sciences--Costa Rica--Societies, etc.--Directories.
Princeton subject headings:
Environmental protection--Costa Rica--Societies, etc.--Directories.