John P. Pratt Defense of April Sixth John P. Pratt To the editor: The review of John Lefgren’s April Sixth by S. Kent Brown, C. Wilfred Griggs, and H. Kimball Hansen (Summer 1982) claims that Lefgren’s work “abounds in unjustified assumptions, misinformation, and misunderstandings.” But, on the contrary, Lefgren’s book contains valid scientific research, giving…