I'm an engineer/physicist by training, and typically, my publications are in journals where the readers do have an semi-advanced understanding of math, but not at a serious mathematician's level. So often, when I use some transform or a function that is not known to the community, I'd like to point them to a reference that's precise, yet simple to read and readily accessible. It seems unfair to point them towards a dense article/book that might be the best in the field, yet completely useless to someone reading my paper.
What I'm looking for, would be an online form of the Encyclopedic Dictionary of Mathematics (EDM), which is a remarkable reference. This is my favourite option, but I'd like to know if there are online alternatives (by a trusted body, not a run of the mill math-o-pedias that float around), which makes access easier.
One that comes to mind is Wolfram MathWorld (WM), which although impressive, can be lacking at times (to put it this way, they have very good references on mathematical concepts that Mathematica is capable of doing). The Digital Library of Mathematical Functions (DLMF) is not bad either, but doesn't come close to the EDM.
Lastly, Wikipedia (WP) is pretty decent, especially in conveying concepts to the lay reader. However the anyone-can-edit it feature makes it a little less reliable than the other three.
For now, my feeling is that EDM $\gt$ WM $\approx$ DLMF $\geq$ WP. Do you have suggestions?
If you think otherwise of my rating of the references, please do let me know why... perhaps I might have overlooked a few aspects in evaluating them and am open to reviewing them.