| 1 | Forages: The Science of Grassland Agriculture 2003. Barnes R.F., Nelson C.J. Collins, M., and Moore K.J. Iowa State Press. |
| 2 | Harvested Forages 1999. Horrocks R.D., and J.F.Vallentin. ISBN 0080533310, 9780080533315 |
| 3 | Alfalfa and Alfalfa Improvement, 1988. A.A.Hanson, D.K.Barns and R.R. Hill. JR. ASA, CSSA, SSSA, Madison Wisconsin, USA. |