- README.md: the edX page for "Calculus 1B: Integration" (18.01.2x) returns
404; the course now lives on MITx Online.
- extras/readings.md: Peter Smith's "Category Theory: A Gentle Introduction"
PDF was removed from logicmatters.net; link to its successor, "Introducing
Category Theory", which he publishes at the same site.
- coursepages/ostep/README.md: the billmei/ostep-projects branch that hosted
the reverse project is gone (404); link to the project in the upstream
ostep-projects repository, which the page already uses elsewhere.
Kish Siva
e5c126d120