Perhaps you should try some spelling variations:
hieu hieu » hien hieu, hieu hien, thien hieu
danh vai » danh sai, danh va, doanh van
cac nuoc » cap nuoc, dat nuoc, cua nuoc
vai cua » dai cua, hai cua, lai cua
va danh » va dinh, va dan, va hanh
tu sach » thu sach, su sach, te sach
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
cua tre » cua te, cuu tre, cua triet

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