"Digital Logic Design" by Aaron Tan is a valuable resource for:

Imagine you are debugging a JK Flip-Flop master-slave configuration at 2:00 AM. You use Ctrl+F (Find) in the PDF, type "master-slave," and jump instantly to the relevant slide. You cannot do that as quickly with a physical textbook.

Sequential logic introduces the element of time and memory into digital design. Go to product viewer dialog for this item.

For the absolute beginner, start with Aaron Tan’s chapters 1–3. For the advanced designer, skip to his memory and Verilog sections.