I was scrolling through this wonderful place as you do; and found this really good link that someone posted that explained all the different kind of lighting techniques you need to know to be able to create semi realistic art. First explanation of lighting ive ever seen that has made sense to me

Like an idiot i didnt save it. Do any of you know or have that link? It was a 30 ish minute youtube tutorial where a dude was drawing his own hand and going through all the different lighting techniques youd need to be across to be able to draw it competently.

If no one does; can you point me in the right direction of what i need to be able to shade/ light my drawings right? i figure its a must for coom art.