https://www.bioactualites.ch/cultures/tracanimale-fr.html
https://www.reseaufaireacheval.fr/usage/traction-animale-agriculture
https://assoprommata.org/spip.php?rubrique6
http://www.civam-bretagne.org/files/fil_bd/Energie/Rapport_Etude_TA_Bretagne.pdf