| Resource | Type | Link / Access | |----------|------|----------------| | Differential Equations by Paul Dawkins (Lamar University) | Free online notes + problem sets | tutorial.math.lamar.edu | | MIT OCW 18.03 (Differential Equations) | Video lectures + PDF notes | ocw.mit.edu | | Elementary Differential Equations by William F. Trench (Open Access) | Free PDF textbook | digitalcommons.trinity.edu | | NPTEL – Differential Equations for Engineers (IIT Madras) | YouTube + transcripts | nptel.ac.in | Dr. B.D. Sharma’s Differential Equations is a solid, problem-rich textbook for undergraduate-level DEs. While PDF downloads are widely searched for, obtaining a legal copy supports the author and ensures you get the latest edition with correct problem solutions. Use library access, purchase a used copy, or leverage free open-source alternatives to learn the subject effectively. Would you like help with a specific differential equation problem or concept from Dr. Sharma’s book instead?