Perhaps you should try some spelling variations:
nam thuoc » nam thuc, nha thuoc, cay thuoc
hoc sach » hoc sinh, hoc cac, hoc anh
tang xa » trang xa, tang ma, lang xa
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
ky tang » ky nang, ky dang, kho tang
tai cua » thai cua, tai cuc, tri cua
cua tre » cua te, cuu tre, cua triet
va dao » ca dao

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sach ky tang xa hoi. hieu va ((nam thu) or (nam thuoc)) ((va dau) or (va dao)) tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ky tang xa hoi. hieu va ((nam thu) OR (nam thuoc)) ((va dau) OR (va dao)) tai cua tre.
• Adding a wildcard symbol may retrieve word variants: hoc sach ky tang xa hoi. hieu va ((nam thu) or (nam thuoc)) ((va dau) or (va dao)) tai cua tre*.