: Some independent math blogs focus on specific, difficult chapters. A notable example is positron0802's Chapter 13 (Field Theory) solutions
If you must look at the full solution, do not just read. Copy it by hand into a notebook, but add marginal annotations: solutions to abstract algebra dummit and foote
For the "extra-hard" starred problems, MathStackExchange is the primary resource. Almost every difficult problem in the book has been discussed, dissected, and solved there, providing multiple perspectives on a single proof. University Course Pages: : Some independent math blogs focus on specific,