I cannot share Phil's enthusiasm for the cited by tool as expressed elsewhere. When I read the words "cited by" I assume that It will then be followed by the name of the resource or the author who is doing the citing (implicit in the preposition "by").. This is not what we see. What we see are the citations, we then need to hover over the citations to find the name of the resource and its author:

One example of how confusing this is (for me, imho, etc.):

What is in Blue here ought be the "author, resource" or simply "resource". Currently, it almost always is the same as the first line appearing under it (the section heading of the resource)
Hovering over the resource gives me the cited by information:

Aaah. The Bible Knowledge Commentary. Not interested. Moving Along. I should know that this is the Bible Knowledge Commentary without having to hover in a tool called "cited by"
What is Mark 7:37 in the greyed out bit at the bottom of the excerpt and in the bottom right corner of the hover box. Is this just a badly tagged resource?
I had some examples from using the greek lexicons (Phil's approach) but I've lost or deleyed them. Personally, it's even worse for finding information on Greek words (imho, etc.)