Most engineering college libraries have 10-15 copies of Mittle. You can scan specific chapters (for personal use) legally under "fair use" provisions.
Before the era of CAD (Computer-Aided Design) and finite element analysis (FEA), designing a motor or generator was a ritual of slide rules, reference tables, and iterative calculations. Mittle’s book preserves this foundational logic. design of electrical machines by v n mittle pdf