Wittaya Ngeontae. 2007. Synthesis of chemically modified silica gel for preconcentration of heavy metals. Faculty of Science, Chulalongkorn University;
Wittaya Ngeontae. (2007) Synthesis of chemically modified silica gel for preconcentration of heavy metals . Chulalongkorn University/Bangkok.
Wittaya Ngeontae. Synthesis of chemically modified silica gel for preconcentration of heavy metals. . Bangkok:Chulalongkorn University, 2007.
Wittaya Ngeontae. (2007) Synthesis of chemically modified silica gel for preconcentration of heavy metals . Chulalongkorn University/Bangkok.