@article{HHA_2006_8_1_a8,
     author = {Pepijn van der Laan and Ieke Moerdijk},
     title = {Families of {Hopf} algebra of trees and pre-lie algebras},
     journal = {Homology, homotopy, and applications},
     pages = {243--256},
     publisher = {mathdoc},
     volume = {8},
     number = {1},
     year = {2006},
     doi = {10.4310/HHA.2006.v8.n1.a8},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4310/HHA.2006.v8.n1.a8/}
}