Excellent work! There are a few things you might be able to improve. Below I have a manipulated image of your reference with a filter. The white/yellow parts are the highlight, the green is the midtone, the blue is the shadow tones (which include core shadow, reflected light and cast shadow). You are missing some midtone on the bridge of the nose, yours seems to go too sharply from highlight to core shadow. This is more pronounced in the ball of the nose, where a fair amount of midtone is missing. On the nasal ala (wing of the nose) you have a highlight, that's not actually there, it's all midtone. It simply looks lighter because of all the surrounding darker areas. This is an easy and common mistake to make. When in doubt, think about the planes and the light. There are no planes on the ala that face the light directly, so there shouldn't be a highlight. And remember, midtone is part of the light family, and darkest light should be lighter than the lightest dark. And one last point I wanted to make, the contrast seems a little high, you went quite dark with the shadows. This may be intentional to create a better picture, but for Bargue studies, since part of the practice is to discipline control of the values, next time you could challenge yourself to match a more subtle overall look. This will probably take more time, as you will need to build values up slower. But it is quite rewarding. Hope this helps, really great work, keep on sketching!

Nice work! For improvement, work on your transitions from light to shadow. They seem a little abrupt. Also, of you want to emulate Bauman, look at his edge work. He doesn't use many outlines, though when he does, they're vary intentional. Keep it up!