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Acknowledge ments I gratefully acknowledge all those who have contributed to the preparation of this thesis. Especially, I would like to express my deep
gratitude to my master advisor, Assist. Prof.
Urmat Ryskulov. I have learned from him many things since I became his student. I appreciate the time he spent forgiving tome useful instructions
on how to write a paper, how to search literature
and how to collect data, as well as all his constructive remarks and comments concerning my thesis. Furthermore, I am thankfully to all the other professors of Epoka University who have contributed in my general academic formation. Finally the most
special thanks go to my family, who has supported me
throughout all of my studies, especially to my sister.
