Perhaps you should try some spelling variations:
hanh trinh » canh tranh, hanh chinh
nhung cong » dung cong, thong cong, hang cong
hoc thien » hoc hien, hoc thieu, hoc tien
hoc thiet » hoc thieu, hoc thuyet, hoc hien
trinh va » trinh van, trinh vat, trinh ve
van toan » van tan, van thanh, manh toan
van tuan » van quan, van ban, anh tuan

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

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