books I know to be good
“Fundamentals of Flight” by Richard Shevell
“Aircraft Performance” by Austyn Mair and David Birdsall
"Gas Turbine Performance by Philip Walsh and Paul Fletcher
For underlying principles
“Engineering Thermodynamics: Work and Heat Transfer” by Rogers and Mayhew
“Electrical Technology” by Hughes
“A Practical Introduction to Electronic Circuits” by Martin Hartley Jones
Schaum's Outline Series on .... such as algebra, calculus, laplace transforms
I do not recommend Barnes McCormick, Jack Mattingly, Tom Benson. I do not like works where the messenger and the presentation become more important than the message nor works where elaborate procedures and page after page of scribbles produce results so wide of the mark.