Columbia subject headings:
Larynx--Diseases--Case studies.
Respiratory organs--Diseases--Case studies.
Trachea--Diseases--Case studies.
Harvard subject headings:
Larynx--Diseases--Case studies.
Larynx--Diseases.
Respiratory organs--Diseases--Case studies.
Trachea--Diseases--Case studies.
Trachea--Diseases.
Princeton subject headings: