Perhaps you should try some spelling variations:
hieu viec » nhieu viec, hieu ve, sieu viet
thu sach » thuat sach, thuoc sach, thu hoach
viec cac » vien cac, viec cua, viec lam
tu sach » su sach, te sach, tu cach
va hang » van hang, va nang, va lang
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
cac tu » cac thu, cach tu, cac du
va cua » va chua, via cua, ca 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)) y nang cao chat. hieu viec cac tu va hang va cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (thu sach)) y nang cao chat. hieu viec cac tu va hang va cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (thu sach)) y nang cao chat. hieu viec cac tu va hang va cua tre*.