Perhaps you should try some spelling variations:
hieu van » thien van, lieu va, hieu ve
tu sach » thu sach, su sach, te sach
cau duc » cau luc, chu duc, cau truc
danh vi » hanh vi, dinh vi, danh di
va danh » va dinh, va dan, va hanh
cao duc » dao duc, cao suc, giao duc
cua tre » cua te, cuu tre, cua triet
sach ly » sach y, sach lo, sach ty
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
ly nang » ky nang, ly hang, ly vang
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 ly nang xa hoi. ((hieu van) or (hieu va)) ((cau duc) OR (cao duc)) va danh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ly nang xa hoi. ((hieu van) OR (hieu va)) ((cau duc) OR (cao duc)) va danh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ly nang xa hoi. ((hieu van) or (hieu va)) ((cau duc) OR (cao duc)) va danh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ly nang xa hoi. ((hieu van) or (hieu va)) ((cau duc) OR (cao duc)) va danh vi cua tre*.