Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
hieu van » hieu va, thien van, lieu va
hanh di » hanh vi, hanh de, hang di
luc van » luoc van, luu van, duc van
cau luc » cau truc, cau phuc
van cau » van dau, van hau, van chat
cua tre » cua te, cuu tre, cua triet
tang ma » mang may, tang van
tang xa » trang xa, lang xa, tang ha
tu sach » thu sach, su sach, te sach
di cua » dai cua, doi cua, de cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu hoach) or (tu sach)) ky ((tang xa) OR (tang ma)) hoi. hieu van cau luc van hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu hoach) OR (tu sach)) ky ((tang xa) OR (tang ma)) hoi. hieu van cau luc van hanh di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu hoach) or (tu sach)) ky ((tang xa) OR (tang ma)) hoi. hieu van cau luc van hanh di cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thu hoach) or (tu sach)) ky ((tang xa) OR (tang ma)) hoi. hieu van cau luc van hanh di cua tre*.