Framed ink - victorcloux
V1, p
Gesture drawing - Ryan Woodward
R1, p31
Design Elements: A Graphic Style Manual
R1,
Drawing on the Right Side of the Brain
R1,
Color: A Visual History from Newton to Modern Color Theory
R1,
插画视觉语言 在理论与实践中学习插画 - alan male
R1, p44