Perhaps you should try some spelling variations:
lang van » dang van, hoang van, giang van
tang van » dang van, hoang van, trong van
nam thuc » nam thuoc, am thuc, nam thu
vat hanh » vat thanh, van hanh, va hanh
vu sach » vu bach, su sach, vu khach
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
va nam » van nam, ha nam, va nay
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: vu sach ky ((lang van) or (tang van)) hoi. hieu va nam thuc vat hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky ((lang van) OR (tang van)) hoi. hieu va nam thuc vat hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: vu sach ky ((lang van) or (tang van)) hoi. hieu va nam thuc vat hanh vi cua tre*.