Perhaps you should try some spelling variations:
hieu viec » nhieu viec, hieu ve, sieu viet
cao hoat » cac hoat, co hoat, cao chat
viec cac » vien cac, viec cua, viec lam
tu sach » thu sach, su sach, te sach
va hang » van hang, va nang, va lang
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo
y nang » ky nang, ly nang, may nang
v nang » va nang, vu nang, van nang
cac tu » cac thu, cach tu, cac du

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