1. 1. DW Ashman, and JE Dutrizac . In: ed. CIM, Calgary, Canada, 1998 : 783 -809 .
2. 2. JM Floyd, and PJ Mackey . In: Extraction metallurgy '81 , IMM, London, 1981 : 345 -377 .
3. 3. LM Fontainas, RH Maes, and JM Cigan . In: ed. Lead-Zinc-Tin '80 , TMS, Warrendale, 1980 : 375 -393 .
4. 5. E Jak, S Degterov, PC Hayes, and AD Pelton . In: ISS, Warrendale, PA, 1997 : 621 -628 .