LBJ was doing Doris Kerns (Goodwin) the Harvard professor, plagiarizing author, PBS "expert" perennially waxing ecstatic as she sings the praises of Landslide Lyndon.
The citation occurs on page 90 of The Texas Connection, Craig I. Zirbel, Warner, 1991, and is credited in the endnotes to page 203 of It Didn't Start With Watergate, Victor Lasky, Dial, 1977.
The Lasky citation was confirmed to me by email from Lucianne Goldberg who explained she was Victor Lasky's agent for his books.
LBJ led a corrupt political career based on vote fraud, having assisted in 1960 by "delivering" Texas to JFK.
He was likely a player in the JFK hit for scores of reasons, the main being he was to be dropped from the 1964 ticket, notwithstanding a lifelong lust for the Oval Office.
Earle Cabell was mayor of Dallas at the time of the JFK hit. His brother Charles Cabell was Deputy Director of CIA and fired by JFK.
JFK's National Security Action Memorandum No. 263 of October 11, 1963 removing U.S. advisors from South Vietnam, was reversed by LBJ's National Security Action Memorandum No. 273 of November 26, 1963 (the first business day after the JFK funeral), referencing objectives "as stated in the White House statement of October 2, 1963".
His conduct of the war was despicable, and cost the tens of thousands of lives on the Wall, and lost the victory which could have been--had he listened to the Joint Chiefs November, 1965.
He died in 1973, the best thing he ever did for America.