Perhaps you should try some spelling variations:
hieu quan » lieu quan, thien quan, lien quan
thu sach » thuat sach, thuoc sach, thu hoach
tu sach » su sach, te sach, tu cach
va hang » van hang, va nang, va lang
hang di » hang doi, hang vi, hang dien
cua tre » cua te, cuu tre, cua triet
nam tu » nam thu, nam thuc
di cua » dai cua, doi cua, de 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) OR (thu sach)) ky nang x ho. ((hieu quan) or (hieu qua)) nam tu va hang di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ky nang x ho. ((hieu quan) OR (hieu qua)) nam tu va hang di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (thu sach)) ky nang x ho. ((hieu quan) or (hieu qua)) nam tu va hang di cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (thu sach)) ky nang x ho. ((hieu quan) or (hieu qua)) nam tu va hang di cua tre*.