Marko created the Age 6 drawings by following the step-by-step instruction in Grumbacher how-to-draw-books, though the occasional fancy labels are entirely his own.
The Age 12 materials are either from a how-to-draw-faces book, or copied from two Gary Larson cartoons, or copied from an entomology book. The doodle on yellow paper came out of a lecture that was not completely absorbing.