Nolan, J. (December 2003). There are numerous points where three countries meet. Are there any with four?. Geographical[en]. 75 (12): 19. ISSN0016-741X.
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Nolan, J. (December 2003). There are numerous points where three countries meet. Are there any with four?. Geographical[en]. 75 (12): 19. ISSN0016-741X.