One of the books I still reread. Its not so much about "abstract thinking" but its very good at teaching you to find the real problem & make a decisions. https:

One of the books I still reread. Its not so much about "abstract thinking" but its very good at teaching you to find the real problem & make a decisions. https://www.amazon.com/Thinkers-Toolkit-Powerful-Techniques-Problem/dp/0812928083 https://www.amazon.com/Thinkers-Toolkit-Powerful-Techniques-...