infinit├ęsimal

1986 / Infinitesimals from Leibniz to Robinson: Time to bring them back to school / Victor Harnik / The Mathematical Intelligencer 8 (1986) p. 41 [doi]
2014 / Distinguishing between "change" and "amount" infinitesimals in first-semester calculus-based physics / Joshua Von Korff ; N. Sanjay Rebello / American Journal of Physics 82 (2014) p. 695 [doi]