According to Moser, Sontag Wrote It

"Out in September, Sontag: Her Life by Benjamin Moser lays out textual and anecdotal evidence that [Susan] Sontag was not only the unofficial co-author of the 1959 analysis of Freud, which has long been known. Then in her 20s, the celebrated writer and filmmaker collaborated on the book with the sociologist [Philip] Rieff, whom she married at the age of 17, just 10 days after attending one of his lectures."

NOTE: In 2025, I read an interesting refutation of this idea. Another author suggests it may be extreme to say that Sontag wrote Rieff's 1959 Freud analysis.