Perhaps you should try some spelling variations:
ban hanh » ban hang
van hanh » van thanh, van anh, van ban
dang mai » dang hai, dang mau, dang bai
tu sach » thu sach, su sach, te sach
cao luc » bao luc, cao duc, cao suc
hieu va » lieu va, hieu qua
mai hoi » mai khoi, dai hoi, lai hoi
ky dang » ky nang, ky danh
vu sach » vu bach, su sach, vu khach
cua tre » cua te, cuu tre, cua triet
va cao » va cac, va co, va dao
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (vu sach)) ky dang mai hoi. hieu va cao luc ((van hanh) or (ban hanh)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (vu sach)) ky dang mai hoi. hieu va cao luc ((van hanh) OR (ban hanh)) vi cua tre.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (vu sach)) ky dang mai hoi. hieu va cao luc ((van hanh) or (ban hanh)) vi cua tre*.