Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
cac tac » cac toc, cac bac, cac dac
va tran » va trang, va trac, ha tran
thi cua » thai cua, thi cuc, tri cua
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, may nang
v nang » va nang, vu nang, van nang

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 ((y nang) OR (v nang)) xa hoi. hieu va ((cac du) or (cac tac)) va tran thi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((y nang) OR (v nang)) xa hoi. hieu va ((cac du) OR (cac tac)) va tran thi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((y nang) OR (v nang)) xa hoi. hieu va ((cac du) or (cac tac)) va tran thi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((y nang) OR (v nang)) xa hoi. hieu va ((cac du) or (cac tac)) va tran thi cua tre*.