There are some links, that I am afraid don't work:

17.14.1 Packages that Org cooperates with

‘calc.el’ by Dave Gillespie
[...] See Section “Embedded Mode” in calc.

# that link doesn't work, it seems it tries to open the file calc.pdf

‘constants.el’ by Carsten Dominik [...] http://www.astro.uva.nl/~dominik/Tools.

# That link is dead. Maybe this would be the correct one: https://staff.fnwi.uva.nl/c.dominik/#orgf869524

Best regards