Perhaps you should try some spelling variations:
viec lam » viec va
cao hoat » cac hoat, co hoat, cao chat
viec cac » vien cac, viec cua, viec va
va hang » van hang, va nang, va hanh
va lang » va nang, hoa lang
tu sach » thu sach, su sach, te sach
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
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 y nang cao hoat. hieu ((viec cac) OR (viec lam)) tu ((va hang) or (va lang)) va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang cao hoat. hieu ((viec cac) OR (viec lam)) tu ((va hang) OR (va lang)) va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang cao hoat. hieu ((viec cac) OR (viec lam)) tu ((va hang) or (va lang)) va cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang cao hoat. hieu ((viec cac) OR (viec lam)) tu ((va hang) or (va lang)) va cua tre*.