Update README.md

README.md

@@ -196,6 +196,8 @@ Blog posts, articles, tutorials, galleries, videos, et cetera.
 - [CuriousMarc: Refilling or Replacing Vintage HP Plotter Pens](https://www.youtube.com/watch?v=h-oj4HrTH14) - Video showing how to open, clean, and refill vintage HP plotter pens.
 - [Commodore 1520 Plotter Demonstration](https://www.youtube.com/watch?v=QwPTluBvKLU) - Video of the Commodore 1520 plotter in action, including a cover-off shot of the mechanism.
 - [Vera Molnar: Toward Aesthetic Guidelines for Paintings with the Aid of a Computer](https://rednoise.org/softas/uploads/molnar.pdf)
+- [Tech Tangents: Gold Standard Plotter - HP 7475A](https://www.youtube.com/watch?v=8785ktWD7vQ) - Video with some HPGL and plotter history, plus operating an HP 7475A from an IBM 5160 microcomputer.
+- [curiousmarc.com: HP 7475A Plotter](https://www.curiousmarc.com/computing/hp-7475a-plotter) - A great collection of info, ephemera, plot files, three YouTube videos, and a 3d-printable replacement part for the HP 7475A.
 
 ## Manuals and Ephemera