Calculus -- Shell Method for Volume

Volume by Shell Method On-line

http://tutorial.math.lamar.edu/Classes/CalcI/VolumeWithCylinder.aspx

http://tutorial.math.lamar.edu/Problems/CalcI/VolumeWithCylinder.aspx

Khan videos & practice problems

https://www.khanacademy.org/math/old-ap-calculus-ab/ab-applications-definite-integrals/ab-shell-method/e/volumes-of-solids-of-revolution-by-shells

other:

https://www.youtube.com/watch?v=lp3_rmjbxZ8 (not about an axis)

http://mgccc.edu/learning_lab/math/calc/revolutn.pdf

https://math.libretexts.org/Bookshelves/Calculus/Book%3A_Calculus_(OpenStax)/6%3A_Applications_of_Integration/6.3%3A_Volumes_of_Revolution_-_Cylindrical_Shells

Interactive site:

https://activecalculus.org/single/sec-6-2-volume.html