Unit-1
Unit-2
Unit-3
Unit-4
https://tutorial.math.lamar.edu/classes/calciii/partialderivatives.aspx
https://www.whitman.edu/mathematics/calculus_online/chapter14.html
Unit-5
https://courses.lumenlearning.com/boundless-calculus/chapter/multiple-integrals/
https://nitkkr.ac.in/docs/5-Multiple%20Integrals%20and%20their%20Applications.pdf
https://ocw.mit.edu/ans7870/textbooks/Strang/Edited/Calculus/14.pdf
Unit-6