2 STRUCTURE OF THE THESIS The main part of the thesis has 135 pages, consisting of the following sections: Introduction: 1 page Chapter 1: Background: 30 pages Chapter 2: Research subjects and methodology: 25 pages Chapter 3: Results: 42 pages Chapter 4: Discussion: 33 pages Conclusions and Recommendations: 3 pages The thesis has 140 references including 16 Vietnamese references and 124 English references, 40 tables, 5 figures, 15 boxes, and 9 appendices.