There is no catalog of PhDs on the internet. In fact the Internet has very little so called facts and most of them can't be verified.
There is no catalog of PhDs on "the internet" but there is Dissertation Abstracts, available through qualified libraries. Including mine.
Through Dissertation Abstracts, you can look up PhD theses for individuals from qualified individuals. Mine is there. Bill Cosby's is there.
AN INTEGRATION OF THE VISUAL MEDIA VIA "FAT ALBERT AND THE COSBY KIDS" INTO THE ELEMENTARY SCHOOL CURRICULUM AS A TEACHING AID AND VEHICLE TO ACHIEVE INCREASED LEARNING.
COSBY, WILLIAM HENRY, JR. University of Massachusetts Amherst, ProQuest Dissertations Publishing, 1976. 7706369.
Martin Luther King, Jr.'s is there.
A COMPARISON OF THE CONCEPTIONS OF GOD IN THE THINKING OF PAUL TILLICH AND HENRY NELSON WIEMAN
KING, MARTIN LUTHER, JR. Boston University Graduate School, ProQuest Dissertations Publishing, 1955. 0024708.
Heck, Dr Laura Schlessinger's is there
EFFECTS OF INSULIN ON 3-O-METHYLGLUCOSE TRANSPORT IN ISOLATED RAT ADIPOCYTES.
SCHLESSINGER, LAURA C. Columbia University, ProQuest Dissertations Publishing, 1974. 7525718.
Rachel Maddow's Oxford thesis is there
Hiv/aids and health care reform in british and american prisons
Maddow, Rachel. University of Oxford (United Kingdom), ProQuest Dissertations Publishing, 2001. U144977.
However, there is no thesis listed for anyone named Linda Suhler. Now, it could be that Suhler is a married name, and so her PhD could be under her maiden name. If anyone has that info, I can easily check.
Alternatively, she has a PhD from a non-American institution not in Dissertation Abstracts. It's possible, because they don't have all the non-American institutions (Oxford is there, but not everything).
Or it could be that she has a PhD from an American institution that does not deposit in DA. However, these are all non-accredited places aka diploma mills, and anyone with a legitimate PhD in the US will have their thesis in DA.
Finally, she could just be making it up.
Tracking down illegitimate PhD claims through DA is a thing I do, so if anyone has more information about what name to check, I will do it