That would be a typo. It looks like it should be 5:39. I’ll verify that and fix it this evening.
As for the source of this, it came from a compilation of several studies. I used to have the source documented on my computer at home until I had a meltdown at home. I’ve spent some time looking for the original compilation since the meltdown but I haven’t been able to find it back yet. If you would like, feel free to e-mail me. When I find the original source back, I can e-mail it to you. I also should have a link at home that refers to some sources, one of which may be the source I’m trying to find back, but I haven’t had time to go through all of them yet.