Perhaps you should try some spelling variations:
thiet tach » chiet tach, thien hach
thuat tach » thuat sach, thuat mach, thuat tac
nhung cong » dung cong, thong cong, hang cong
cua nhung » va nhung
anh tang » anh bang, anh dang, anh nang
tang cua » mang cua, hang cua, tang luan
dan toan » dan than, manh toan, xuan toan
van toan » van tuan, van tan, van thanh

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((thiet tach) OR (thuat tach)) - anh tang cua nhung cong ((dan toan) or (van toan)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thiet tach) OR (thuat tach)) - anh tang cua nhung cong ((dan toan) OR (van toan)) cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thiet tach) OR (thuat tach)) - anh tang cua nhung cong ((dan toan) or (van toan)) cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((thiet tach) OR (thuat tach)) - anh tang cua nhung cong ((dan toan) or (van toan)) cau*.