Perhaps you should try some spelling variations:
nang mai » nang ma, nang tai, lang mai
dua tren » dung tren
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cuu tre » cua tre, cau tren, cau treo
hieu ve » hieu va, hieu van
mai hoi » mai khoi, dai hoi, lai hoi
xuc va » duc va, tuc va, xac va
ve cac » va cac, vien cac
luc va » duc va, tuc va, loc va

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 ky nang mai hoi. hieu ve cac ((xuc va) OR (luc va)) hanh vi ((dua tren) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang mai hoi. hieu ve cac ((xuc va) OR (luc va)) hanh vi ((dua tren) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang mai hoi. hieu ve cac ((xuc va) OR (luc va)) hanh vi ((dua tren) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang mai hoi. hieu ve cac ((xuc va) OR (luc va)) hanh vi ((dua tren) or (cuu tre))*.