Spellman's Standard Handbook for Wastewater Operators
Spellman's Standard Handbook for Wastewater Operators: Volume I, Fundamental Level, Second Editio
Spellman's Standard Handbook for Wastewater Operators: Volume II, Intermediate Level, Second Edition
Spellman's Standard Handbook for Wastewater Operators: Volume III, Advanced Level, Second Edition
Frank R. Spellman