Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
sach dao » lanh dao
nang mai » nang ma, nang tai, lang mai
cam truc » cau truc, nam truc, lam truoc
va hanh » van hanh, va thanh, va danh
truc va » thuc va, thuc vat, trung va
hieu ve » hieu va
sach lo » sach doi, sach hoi, sach moi
mai hoi » mai khoi, dai hoi, lai hoi
cua tre » cua te, cuu tre, cua triet
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 lo) or (sach dao)) nang mai hoi. ((hieu ve) OR (hieu van)) cam truc va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach lo) OR (sach dao)) nang mai hoi. ((hieu ve) OR (hieu van)) cam truc va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach lo) or (sach dao)) nang mai hoi. ((hieu ve) OR (hieu van)) cam truc va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach lo) or (sach dao)) nang mai hoi. ((hieu ve) OR (hieu van)) cam truc va hanh vi cua tre*.