What is in a name?

[Donna McCreary]

Currently, I am once again reading Mrs. Abraham Lincoln: A Study of Her Personality and Her Influence on Lincoln by W. A. Evans which was publishsed in 1932. I noticed he makes a distinction between using the names "Mary Todd" (for when she was single) and "Mrs. Lincoln" (after she was married) He never used the name "Mary Todd Lincoln." However, William Barton wrote "Mary Todd Lincoln" in his 1927 book, The Women Lincoln Loved.
Honore Willsie Morrow's Mary Todd Lincoln, An Appreciation was published in 1928.

Since Mary never signed, or used the name "Mary Todd Lincoln," I am wondering who was the first author to refer to her as such? Obviously, by the 1920's it was more common to use "Mary Todd Lincoln."