Privilege is either being the recipient of benefits from others work....OR.....for the SJW set.....being so well off that you know longer have to consider the tax burden of increases in welfare programs and disregard the middle class that will shoulder the burden.
That is my new retort after being told that I am privileged by a very leftist friend. I was born in the low class, but through constant work since 15 years of age, being frugal and forgoing luxuries, saving whenever possible, and driving used cars into the ground, I am now trying to enjoy to middle class/upper middle class lifestyle in Southern California. Now I am supposed to feel guilted into taking care of everyone else? It made me so upset. I think the fact that I am not a burden for anyone else, and trying to raise my children so they will be productive members of society, and do occasionally do some charity work is sufficient, thank you very much!!!
I don't have good direct sources on all of it, I ran through second, third, and later generation material. Peggy Mcintosh is a Marxist Intersectional Feminist thought leader of note, but reading her stuff is daunting. I find reading Anita Sarkeesian's master thesis "I'll Make a Man out of You" is a good insight. https://www.academia.edu/4066522/I_LL_MAKE_A_MAN_OUT_OF_YOU1_STRONG_WOMEN_IN_SCIENCE_FICTION_AND_FANTASY_TELEVISION
While you're reading that, note all the anti-capitalist statements on a pass.
For a nice over view of a source idea, but I can't get the book it's on yet, try PSA Sitch's "The Origin of Only White People Can Be Racist". Part 1: https://www.youtube.com/watch?v=ZqqdmRUGoOA Part 2: https://www.youtube.com/watch?v=Ua73gNImLrw
For your own reading, but not great at proving anything to those mired in it, I suggest taking a read of both Christina Hoff Sommers' "Who Stole Feminism" and Stephen Hicks "Explaining Postmodernism". The latter because Intersectional Feminism is a Postmodernist field.
An interesting read after "Explaining Postmodernism" would be "The God that failed". A book of 6 essays from Communist authors around the early and mid 1900s. It's eerie how many things from the German author reflect things happening today in higher education and in many companies.
I wish you luck with your friend, but I caution you and thinking evidence or reason is going to be all you need. That can get frustrating. There's interviews with Yuri Bezminov that go over this. Here's a 9 minute clip from an interview with him. https://www.youtube.com/watch?v=pgCnpCBORyM I highly recommend watching this one.