1. Nitrogen uptake in relation to water availability in wheat;Abreu;Plant Soil,1993
2. The efficiency of nitrogen under Mediterranean conditions the case of Portugal;Alves,1988
3. Efeito do déficit de água no aproveitamento de nitrogénio-15N na cultura do trigo;Boaretto;Anais da E.S.A. “Luiz de Queiroz”,1982
4. Efficiency in uptake and use of nitrogen by plants;Bowen,1991
5. Diffusion method to prepare soil extracts for automated nitrogen-15 analysis;Brooks;Soil Sci. Soc. Am. J.,1989