Perhaps you should try some spelling variations:
hanh hai » thanh hai, nhanh hai, hang hai
hieu van » thien van, lieu va, hieu ve
trung va » truong va, trang va, trung ha
su sach » so sach, vu sach
hai cua » thai cua, dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
ty nang » ky nang, ty xang, ty hang

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 nang xa hoi. ((hieu van) OR (hieu va)) nam ((duc va) or (trung va)) hanh hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty nang xa hoi. ((hieu van) OR (hieu va)) nam ((duc va) OR (trung va)) hanh hai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty nang xa hoi. ((hieu van) OR (hieu va)) nam ((duc va) or (trung va)) hanh hai cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ty nang xa hoi. ((hieu van) OR (hieu va)) nam ((duc va) or (trung va)) hanh hai cua tre*.