1. Aldezabal A 2001. El sistema de pastoreo del Parque Nacional de Ordesa y Monte Perdido (Pirineo central, Aragón). Interacción entre la vegetación supraforestal y los grandes herbívoros. Consejo de Protección de la Naturaleza de Aragón, Zaragoza, Spain.
2. Official methods of analysis 18th edition (1st revision),2006
3. The effect of herbage allowance upon the herbage intake and performance of suckler cows and calves;Baker;Grass and Forage Science,1981
4. GT Barthram 1986. Experimental techniques: the HFRO swardstick. In The Hill Farming Research Organisation Biennial Report 1984–85. HFRO, Bush Estate, Penicuik, Midlothian, UK, pp. 29–30
5. Diet selection by sheep and goats on Mediterranean heath-woodland range;Bartolomé;Journal of Range Management,1998