1. El sistema de pastoreo del Parque Nacional de Ordesa y Monte Perdido (Pirineo central, Aragón). Interacción entre la vegetación supraforestal y los grandes herbívoros;Aldezabal,2001
2. The ecological role of the goat in maintaining pasture and range;Allan,1996
3. Official Methods of Analysis;AOAC,1990
4. The effect of herbage allowance upon the herbage intake and performance of suckler cows and calves;Baker;Grass Forage Sci.,1981
5. Experimental techniques: the HFRO swardstick;Barthram,1986