Heathkit Design Series
They're all out of print now (as are all of the decent educational materials they ever had), but the Heathkit "Design Series" of books were wonderful in that regard. They were somewhat "cookbooky" and had served several different areas of electronics. There's a set covering "Transistor Circuits", another for "Digital Circuits", another for "Analog Electronics", etc. These are not the usual yellow and blue Heathkit books but are blue print on a gray background. Maybe you can find them on ebay. Most came in two volumes. Not of the design series, but equally a good text is the "Operational Amplifiers" course that Heathkit had. It was a part of their analog series that included "Timers", "Optoelectronics", "Phase-Locked Loops" and "Active Filters". Both the Operational Amplifiers book and the Active Filters book were very good. Both are written by Howard Berlin, whom I respect very much, and both are mirrored in Howard W. Sams books. I believe the Sams titles are "Operational Amplifiers with Experiments" and "Active Filters with Experiments". I don't know if they're still in print by Sams or not. Heath killed them off long ago, replacing all those good courses with a single ring-binder of quickie courses that really sucked. Heath went so far downhill after killing off their kit line that a year or mourning should take place.
Dean