ways to correct keystoning/ perspective in photoshop elements

I've been using the scanner for little pictures but larger pictures just don't work. I cannot take a square picture so I always have to correct it.
Here are some links for that:

• https://digital-photography-school.com/how-to-fix-keystone-issues-in-photoshop-elements/
• https://digital-photography-school.com/correcting-perspective-in-photoshop-and-photoshop-elements/
• http://www.essential-photoshop-elements.com/straighten-leaning-buildings.html
• http://www.photoshopessentials.com/photo-editing/keystoning/

A lot more messing around than in my old photoshop program but still doable.

Secret Knowledge by David Hockney

Secret Knowledge
rediscovering the lost techniques of the old masters
by David Hockney
isbn: 0-670-03026-0

Very interesting book. Lots of examples. He presents his case that many of the old masters probably used optical devices such as the camera lucida to make their paintings. He shows subtle clues from the paintings that indicate that optical devices were used. He also recreates experiments showing the effect of optical devices on sketches and paintings.

4x6 pen sketches, hart park