@article{HHA_2020_22_2_a9,
     author = {B.O. Bainson and N.D. Gilbert},
     title = {The homology of principally directed ordered groupoids},
     journal = {Homology, homotopy, and applications},
     pages = {163--172},
     publisher = {mathdoc},
     volume = {22},
     number = {2},
     year = {2020},
     doi = {10.4310/HHA.2020.v22.n2.a10},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4310/HHA.2020.v22.n2.a10/}
}