Mary Kathryn Burton (12 July 1925 - 4 March 2012). Appears to have traded under the name of M. K. Burton Books as a mail-order concern using a Box 447 address in Ann Arbor from ca. 1963-1966. She was a member of the A.B.A.A.
See Sheppard's Book Dealers in North America (1963-1965) and the AB Bookman's Yearbook for 1966.
Public records note the marriage of Mary Kathryn Rutten to Robert Edward Burton on 30 July 1949 in Detroit.
R. E. Burton (noted as a co-owner of M. K. Burton in the 1965 Bowker American Book Trade Directory) had been hired by the University of Michigan as the director of its Science and Engineering libraries in 1962.