The Art of Comic Book Inking, by Gary Martin

Inking is one of those aspects of graphic novels that goes largely unnoticed – unless it’s done poorly. Pencilers, those artists who do the sketches, tend to get the kudos for a comic’s artwork. Inkers, though, are largely responsible for the artwork’s tone, controlling such things as shading and making elements pop out from the page.
This book offers a good glimpse into that world. It covers myriad inking styles and includes commentary from some of the bigger names in this relatively obscure business.