Other
Magnet Sales & Manufacturing: Permanent Magnet Design Guide
Very advanced information about permanent magnets and how they are constructed. Covers different functions they perform, the four classes of commercial magnets, how magnets are measured, design considerations, the B-H curve, calculations...
Lumen Learning
Lumen: Boundless: Magnetism and Magnetic Fields: Permanent Magnets
This short module covers permanent magnets, the concept of polarity, and the manufacture of permanent magnets. Includes some quiz questions.