That particular book is of special interest to me as a stirner shill/fanatic. The "Specter of Marx" he's refering to is Max Stirner! Derrida is trying to answer

That particular book is of special interest to me as a stirner shill/fanatic. The "Specter of Marx" he's refering to is Max Stirner! Derrida is trying to answer the question of "Why did Stirners book, The Unique and its Property, trigger Marx to write The German Ideology and dedicate over 300 pages to shitting on stirner?". I've cover to cover read that book, and it's garbage dog shit just like Zizek is. The moment that you start trying to wax poetic about whose what ism is when you become post-modern neo marxism. It's academic ivy league eliteist careerism and its disgusting. Fashionable nonsense. Zinn and Zizek are playing the exact same game. One just writes more coherently than the other. If you think Hegel or Marx are worth citing, you're a pomo/fraud. If you think Psychoanalysis/Freud are worth citing, you're a pomo/fraud. Deleuze killed himself. Mark fischer killed himself. Althussar killed his wife. Wilhelm Reich was a loony who after writing his analysis of the sexuality of fascism went nuts about "Orgone" machines. Foucault, Sartre/De Bouvier were pedos and collaborators. Even my favorite half-breed of pluralism mixed with pomo shit, Arendt, was in love with the arch nemesis of "oh they were literally a nazi " pomos - Heidigger! And who can forgot Carl Schmitt? JUST WRITE THESE IDIOTS ALL OFF ALREADY AND LEAVE THEM IN THE DUST BIN OF HISTORY!