memoirs by first ladies of the United States
... that several memoirs by first ladies of the United States have outsold books written by their presidential husbands?
... that several <b id="mwAt8"><a href="./List_of_memoirs_by_first_ladies_of_the_United_States" id="mwAuA" rel="mw:WikiLink" title="List of memoirs by first ladies of the United States">memoirs by first ladies of the United States</a></b> have outsold books written by their presidential husbands?