Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hanh tai » thanh tai, hang tai, han tai
duc manh » suc manh, duc anh, duc minh
nam duc » nam duoc, pham duc, nam thuc
sach ty » sach y, sach thu, xach tay
lang xa » lang ha, dang xay, lang van
sach tu » sach thu, cach tu, sach uu
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: su ((sach ty) OR (sach tu)) lang xa hoi. hieu van nam duc manh ((thanh san) or (hanh tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ty) OR (sach tu)) lang xa hoi. hieu van nam duc manh ((thanh san) OR (hanh tai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ty) OR (sach tu)) lang xa hoi. hieu van nam duc manh ((thanh san) or (hanh tai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) OR (sach tu)) lang xa hoi. hieu van nam duc manh ((thanh san) or (hanh tai)) cua tre*.