BibTex format
@article{Doering:2008:10.1063/1.2883826,
author = {Doering, A and Isham, CJ},
doi = {10.1063/1.2883826},
journal = {JOURNAL OF MATHEMATICAL PHYSICS},
title = {A topos foundation for theories of physics:: IV.: Categories of systems},
url = {http://dx.doi.org/10.1063/1.2883826},
volume = {49},
year = {2008}
}