Tornadoes. Papers on tornadoes: The 13 tornadoes of Mar. 28, 1920 [articles by C. L. Mitchell and others]; The 4 tornadoes of Apr. 20, 1920 [articles by J. H. Jaqua and others]; Tornado in Union County, N. C., Apr. 12, 1920, [by] G. S. Lindgren; Tornadoes in northeastern Oklahoma, May 2, 1920, [by] J. A. Reihle; Tornado and its cause, [by] W. J. Humphreys; Principal publications containing statistics of tornadoes in United States, [by] C. F. Talman.

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