Reference. Differential geometry in toposes [kostecki2009differential]

✍️source

@misc{kostecki2009differential,
 title = {Differential Geometry in Toposes},
 author = {Kostecki, Ryszard Pawe{\l}},
 year = {2009},
 url = {https://www.fuw.edu.pl/~kostecki/sdg.pdf},
 publisher = {Citeseer}
}