When I first started learning to draw on my own instead of copying illustrations, I had it in my mind that looking at a picture for reference was a form of cheating. This isn’t true; if you don’t know how to draw something it’s not cheating to have reference material. In fact, your art will be better for it. If you don’t know how to draw something, it’s best to find out how to draw it by looking at the real thing, whether it be an object you have or through a photograph. I wouldn’t recommend using another illustrators image as reference, just for the fact that they may have stylized the object in their own way and is no longer accurate.