- added references to the method doc
- added references to the method doc

StongeEtienne/dipy,matthieudumont/dipy,JohnGriffiths/dipy,JohnGriffiths/dipy,villalonreina/dipy,StongeEtienne/dipy,nilgoyyou/dipy,FrancoisRheaultUS/dipy,FrancoisRheaultUS/dipy,nilgoyyou/dipy,matthieudumont/dipy,villalonreina/dipy