This book highlights a series of new itinerant electron models proposed based on the experimental results of electron spectra obtained since 1970. Although conventional magnetic ordering models were established before 1960, many problems remain to be solved. The new models in this book include an O 2p itinerant electron model for magnetic oxides, a new itinerant electron model for magnetic metals, and a Weiss electron pair model for the origin of magnetic ordering energy of magnetic metals and oxides. With these models, the book explains typical magnetic ordering phenomena...