@article{10_4153_CJM_1966_006_6,
     author = {Mullin, R. C.},
     title = {On the {Average} {Number} of {Trees} in {Certain} {Maps}},
     journal = {Canadian journal of mathematics},
     pages = {33--41},
     year = {1966},
     volume = {18},
     number = {1},
     doi = {10.4153/CJM-1966-006-6},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1966-006-6/}
}