The original document was a six page typed manuscript. When printed in double columns in a 1980 IEEE journal it was only one page, which can be downloaded using the DOI number given above. There is also another version on John's home computer retyped into Microsoft WORD 6 in the 1990's. (Bonnie did not  add typed math symbols which would have been added by John but he never did proof read the MS WORD file, so if recreating this paper, one needs to refer to the PDF scanned version of Warfield's original typed manuscript which has correct math notations throughout placed there by Warfield. (Rose Warfield found the publisher's offprint later on and scanned it, the offprint of course is also correct.) This material was shipped to Fenwick Library Special Collections, George Mason University, Fairfax, VA on 23 October 2000. A paper offprint of full text is at Fenwick Library, Box 05/02, C0016, SCRC, George Mason University Libraries.

 r.w. Circa 2000, updated 18 April 2015 and January 11, 2018.