Quality improvement in determination of chemical oxygen demand in samples considered difficult to analyze, through participation in proficiency-testing schemes

1. Raposo, F.
2. Fernández-Cegrí, V.
3. De la Rubia, M.A.
4. Borja, R.
5. Beltrán, J.
6. Cavinato, C.
7. Clinckspoor, M.
8. Demirer, G.
9. Diamadopoulos, E.
10. Frigon, J.C.
11. Koubova, J.
12. Launay, M.
13. Méndez, R.
14. Menin, G.
15. Noguerol, J.
16. Uellehdahl, H.
17. West, S.