<human>: Can you succinctly summarize the text in 1-3 sentences?

Early next week I have an interview where I've been asked to bring three references. I have two solid ones (very recent, I'm sure they'll say good/honest things), but I'm struggling with my third.

I am needing to choose between a professor who I had Fall 2012 and someone I worked with recently. I plan to email the professor this afternoon to ask if they mind and to remind them who I am (it's been a little over a year since I last spoke to them and that was just in passing). The other is a friend who I interned with (he has a job in the field I'm applying for, but not the same place). He offered to be referred as a "professional colleague" since I'm having problems. 

Neither one seems like an especially strong choice. I did well in the professor's class, but it's been so long and I worry that they won't have much to say (or they'll refuse) - I never spoke to her outside of class or anything. Using my friend as a reference feels like a bit of a stretch? I know he'd be professional about it, but it seems like a very big favor and I don't know how places of employment feel about that sort of thing.

Normally I wouldn't stress about it so much, but I know this place checks references so I can't use my usual not-so-great ones (I still use the place I worked over five years ago - I think she's retired but apparently no one checks).
<bot>: I have two weak references (an old professor and an ex-coworker), which is the least terrible choice?