Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
hieu viec » nhieu viec, hieu ve, sieu viet
thanh va » thanh van, hanh va, thanh ha
thanh ve » hanh ve, thanh vien, thanh van
viec cac » vien cac, viec cua, viec lam
va triet » va thiet, va trien, ve triet
sach ty » sach y, sach tu, sach thu
cac tac » cac toc, cac bac, cac dac
ty nang » ky nang, ty xang, ty hang
tac va » tac da, tac xa, tuc va
o hoi » co hoi, o hoc, o hai

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: thuoc sach ty nang ((o hoi) or (xa hoi)). hieu viec cac tac va ((thanh ve) OR (thanh va)) va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sach ty nang ((o hoi) OR (xa hoi)). hieu viec cac tac va ((thanh ve) OR (thanh va)) va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc sach ty nang ((o hoi) or (xa hoi)). hieu viec cac tac va ((thanh ve) OR (thanh va)) va triet".
• Adding a wildcard symbol may retrieve word variants: thuoc sach ty nang ((o hoi) or (xa hoi)). hieu viec cac tac va ((thanh ve) OR (thanh va)) va triet*.