1. M. Blanco, S. Maspoch,Mikrochim. Acta 1983,III, 11.
2. S. Maspoch, J. Bartroli, M. Blanco,Mikrochim. Acta 1983,III, 95.
3. Zeng Zuotao, Xu Qiheng,Fengxi Huaxue 1990,11, 983.
4. Zeng Zuotao, Xu Qiheng,Metallurgical Analysis (China) 1990,6, 1.
5. Zeng Zuotao, Xu Qiheng,Fengxi Huaxue 1991,2, 134.