If you finish Oprea and want more applications, next look at Geometric Methods in Physics by Schutz, or Modern Differential Geometry for Physicists by Isham. But first, master Oprea. You won’t regret it.
: Understanding the shortest paths on surfaces. Global Results : The Gauss-Bonnet Theorem and holonomy. If you finish Oprea and want more applications,
While you can find free PDFs via Library Genesis (LibGen) or similar repositories, the best and better way to access this digital text is through: If you finish Oprea and want more applications,