I'm re-starting pen drawing from level 0, so I bought the 3 first books of the "Leonardo Collection". Those are great books in my opinion, and they help me progressing faster.
I choose the coffee mill reference image from book 1, page 12. I love coffee, and my Grand Mother used to use a coffee mill every morning when I was on vacation in her home in my tender youth. I guess this reminds me great and warm moments.
Please, don't hesitate to comment to help me correct mistakes or make adjustments to this Work In Progress.