Particularly with the advent of gangsta rap, many hip hop artists happen to come from underclass backgrounds. Aforementioned artists such as Tupac Shakur, Ice Cube, and Killer Mike have made just as much reference to class oppression as racial oppression. Tupac Shakur used his lyrics incorporated Revolutionary Nationalism. In "Words of Wisdom" from the album "2Pacalypse," Shakur's lyrics underscore the refusal to accept economic inequality and inadequate employment opportunities. Other political rappers, such as Public Enemy, The Dope Poet Society, Dead Prez, The Coup, Paris and Immortal Technique, have advocated explicitly communist views—mostly leaning to Maoism—whereas some rappers such as Lupe Fiasco and the lesser-known Emcee Lynx, P.O.S, and Sole have advocated anarchist positions. Political references have long been made in hip hop culture; some proving to be effective in spurring constructive discussion and others, such as The Coup's originally planned album cover for Party Music—which depicted the destruction of The World Trade Center to signify the fall of capitalism—receiving negative criticisms (although the album art was designed before the September 11 attacks and was changed prior to its November 2001 release).