@article{10_4171_dm_392,
     author = {Andr\'e Joyal and Joachim Kock},
     title = {Coherence for weak units},
     journal = {Documenta mathematica},
     pages = {71--110},
     year = {2013},
     volume = {18},
     doi = {10.4171/dm/392},
     url = {http://geodesic.mathdoc.fr/articles/10.4171/dm/392/}
}