Vector Fields, Divergence and Curl, and Flux and Circulation Integrals (robphy)

(The original 2019 version has been updated in 2022.) This is based on (Vector Fields, Divergence, Curl, and Line Integrals  by  Erik Jacobsen) which is claimed to be based on (presumably) (Vector Fields and Line Integrals by George Sturr). The "Purcell" vector fields are based on E.M. Purcell's Electricity and Magnetism textbook.