[TachyonicBytes]

Would you mind giving us the titles of those books?

[Chris2048]

They are in the attic at the moment, but they are all fairly old books (and terse, dry, basic formatting/illustration), seemingly from a period in time when infitesimals were apparently more popular.

There are a few similar ones on IA, e.g.

https://archive.org/details/in.ernet.dli.2015.148501/page/n8...

On that page the 'h' term is the infitesimal, as in

  d(x^2) / dx = 2x + h

Though I prefer something like 'Δx' to make the link to x more explicit. Would love to see a more modern book on the topic.