Perhaps you should try some spelling variations:
hoc thuyet » hoc chuyen
hanh trinh » canh tranh, hanh chinh
hoc thiet » hoc thieu, hoc hien, toc thieu
trinh han » trinh quan
cong cong » trong cong, dung cong, dang cong
san tran » tan tran, ban tran, dang tran
tran cau » tran chau, toan cau, ran cau

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) OR (hoc thuyet)) tach - hanh trinh han ((cong cong) or (cong dong)) san tran cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc thiet) OR (hoc thuyet)) tach - hanh trinh han ((cong cong) OR (cong dong)) san tran cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((hoc thiet) OR (hoc thuyet)) tach - hanh trinh han ((cong cong) or (cong dong)) san tran cau".
• Adding a wildcard symbol may retrieve word variants: ((hoc thiet) OR (hoc thuyet)) tach - hanh trinh han ((cong cong) or (cong dong)) san tran cau*.