Perhaps you should try some spelling variations:
thu dang » thu hang, thu bang, thu sang
thu dong » thuy dong, tu dong, thu cong
tu sach » thu sach, su sach, te sach
hoc vat » hoc va, hoc viet, thuc vat
hoc van » hoc dan, hoc va, hoc phan
hieu va » lieu va, hieu qua
va cham » va chat, va tham
cua tre » cua te, cuu tre, cua triet
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 ((thu dang) OR (thu dong)) xa hoi. hieu va cham ((hoc van) or (hoc vat)) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((thu dang) OR (thu dong)) xa hoi. hieu va cham ((hoc van) OR (hoc vat)) hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((thu dang) OR (thu dong)) xa hoi. hieu va cham ((hoc van) or (hoc vat)) hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((thu dang) OR (thu dong)) xa hoi. hieu va cham ((hoc van) or (hoc vat)) hanh vi cua tre*.