Columbia subject headings:
Baseball--Law and legislation--United States.
Mass media and sports--Law and legislation--United States.
Professional sports--Law and legislation--United States--History--20th century.
Professional sports--Law and legislation--United States.
Professional sports--United States--History--20th century.
Harvard subject headings:
Professional sports--Law and legislation--United States--History--20th century.
Professional sports--United States--History--20th century.
Princeton subject headings:
Professional sports--Law and legislation--United States--History--20th century.
Professional sports--United States--History--20th century.