Perhaps you should try some spelling variations:
luoc ban » quoc ban, buoc ban, duoc ban
hanh vai » hanh vi, hanh va, hanh tai
luoc can » luc canh, hoc can, luoc dai
vai cua » dai cua, hai cua, lai cua
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
dang xa » dang xay, lang xa, dang ha
ky dang » ky nang, ky danh
cua tre » cua te, cuu tre, cua triet
ve cau » ke cau, va cau, ve cac

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 (thu hoach)) ky dang xa hoi. hieu ve cau ((luoc ban) OR (luoc can)) hanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu hoach)) ky dang xa hoi. hieu ve cau ((luoc ban) OR (luoc can)) hanh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thu hoach)) ky dang xa hoi. hieu ve cau ((luoc ban) OR (luoc can)) hanh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu hoach)) ky dang xa hoi. hieu ve cau ((luoc ban) OR (luoc can)) hanh vai cua tre*.