Perhaps you should try some spelling variations:
hieu quan » lieu quan, thien quan, lien quan
nam thuc » nam thuoc, am thuc, nam thu
lang doi » hang doi, lang dai, lang dong
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
va lang » va nang, hoa lang
doi cua » dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
nam tu » nam thu

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