380 OSCAR W. RICHARDS 



55. Berkson, J., T. B. ]\Iagath, and AI. Hurn, J. Am. Stat. Assoc, 30, 414 



(1935). 



56. Lison, L., Les methodes de reconstruction graphique. Actualites scien- 



tifiques et industrielles, No. 553, Hermann, Paris, 1937. 



COMMERCIAL SOURCES 



57. American Optical Co., Scientific Instrument Division, Buffalo 15, N, Y. 



58. Bausch and Lomb Optical Co., Rochester 2, N. Y. 



59. R. and J. Beck, Ltd., 69 Mortimer St., London, W 1, England. 



60. Cooke, Troughton. and Simms, Kingsway North, York, England. R. 



Y. Fener Co., 110 Pleasant St., Maiden, Mass. (U. S. agents). 



61 . Corning Glass Works, Corning, N. Y. 



62. Eastman Kodak Co., Rochester 4, N. Y. 



63. Farrand Optical Co., Bronx Blvd. and East 238th St., New York 66. 



64. Gaertner Scientific Corp., 1210 Wrightwood Ave., Chicago 14, 111. 



65. E. Leitz, Inc., 304 Hudson St., New York 13. 



66. C. Reichert, Vienna, Austria. 



67. W. Watson and Son, 14 Hadley Grove, High Barnett, London, England. 



68. Carl Zeiss, Inc., 485 Fifth Ave., New York. 



