1. A. Mònico-Pifarré, M. Xirau-Vayreda,J. Assoc. Anal. Chem. 1987,70, 596.
2. World Health Organization,Tech. Rept. Ser. No. 502, WHO, Geneva, 1972.
3. World Health Organization,Tech. Rept. Ser. No. 545, WHO, Geneva, 1974.
4. World Health Organization,Tech. Rept. Ser. No. 592, WHO, Geneva, 1976.
5. M. Maeda, A. Tsuji,J. Chromatogr. 1976,120, 449.