A citrus oil you may not have heard of

This is the source. It's a yuzu, and yuzu essential oil is extracted, like most citrus oils, from the skin. To be honest, I hadn't heard of it myself until I read about it in this post: http://www.quinessence.com/yuzu.htm It works very much like bergamot, apparently. 

Sounds very interesting, though there may be problems getting it. Neither of the suppliers I usually recommend stocks it.

For information on orange oils in general and bergamot oil in particular, you can check out my post here:  http://guidetoaromatherapy.org/essential-oils-guide-orange-oils/