Perhaps you should try some spelling variations:
nang mai » nang ma, nang tai, lang mai
so sach » so sanh, bo sach, co sach
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
hieu ve » hieu van
mai hoi » mai khoi, dai hoi, lai hoi
ty nang » ky nang, ty xang, ty hang
cua tre » cua te, cuu tre, cua triet
xuc va » duc va, luc va, xac va
tuc va » thuc va, truc va, tuc xa
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: so sach ty nang mai hoi. ((hieu ve) or (hieu va)) cam ((xuc va) OR (tuc va)) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ty nang mai hoi. ((hieu ve) OR (hieu va)) cam ((xuc va) OR (tuc va)) hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ty nang mai hoi. ((hieu ve) or (hieu va)) cam ((xuc va) OR (tuc va)) hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach ty nang mai hoi. ((hieu ve) or (hieu va)) cam ((xuc va) OR (tuc va)) hanh vi cua tre*.