WATERGATE AND THE HOAX

From the biography, Citizen Hughes, by Michael Drosnin, published in 1987 by Henry Holt & Co, New York:

"The account of the Hughes-Nixon dealings in [Clifford]
Irving's book was quoted in an unpublished Senate
Watergate Committee report. [White House Chief of Staff]
H.R. Haldeman started getting FBI reports on the Irving
affair directly from [FBI Director] J. Edgar Hoover,
and in early 1972 the White House managed to
obtain a copy of the still-secret manuscript from
a source at McGraw-Hill...

"Nixon read at least a summary of Irving's account.
It came as quite a shock. The $400,000 figure
[concerning the 'loan' from Hughes to Nixon, the amount of which Irving had only guessed at] was probably not far off the mark. The secret figure was so close to fact, [Nixon’s chief domestic adviser] John Ehrlichmann later suggested, that the Hunt-Liddy team was sent to burglarize National Democratic Headquarters at the Watergate in order to discover what Irving might have told the Democrats about the Hughes-Nixon loans. The infamous 17-minute ‘gap’ in the Nixon White House tapes allegedly dealt with that specific subject..."