Perhaps you should try some spelling variations:
nang mai » nang ma, nang tai, lang mai
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
mai hoi » mai khoi, dai hoi, lai hoi
hieu va » lieu va
va danh » va dinh, va dan, va hanh
cua cuu » cua chu, cua cau, cua cu
cac tu » cac thu, cach tu, cac du
ca cuu » cap cuu, ca cua, ca cau

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