Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
thien van » thi van
thu sach » tu sach, thuat sach, thu hoach
hieu van » hieu va, lieu va, hieu ve
van hanh » van thanh, ban hanh, van anh
hanh di » hanh vi, hanh de, hang di
ty nang » ky nang, ty xang, ty hang
cua tre » cua te, cuu tre, cua triet
hac du » cac du, han du, hac de
du van » duy van, duc van, tu van
di cua » dai cua, doi cua, de cua
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu sach) OR (thuoc sach)) ty nang x hoi. ((hieu van) or (thien van)) hac du van hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (thuoc sach)) ty nang x hoi. ((hieu van) OR (thien van)) hac du van hanh di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) OR (thuoc sach)) ty nang x hoi. ((hieu van) or (thien van)) hac du van hanh di cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) OR (thuoc sach)) ty nang x hoi. ((hieu van) or (thien van)) hac du van hanh di cua tre*.