Perhaps you should try some spelling variations:
thanh di » thanh doi, thanh de, thanh do
dua tren » dung tren
tu sach » thu sach, su sach, te sach
cao hoi » cau hoi, cao hoc, tao hoi
hieu ve » hieu va, hieu van
cam duc » cam xuc, cao duc, pham duc
duc gia » quoc gia
cuu tre » cua tre, cau tren, cau treo
y nang » ky nang, ly nang, v nang
co hoi » co hoc, co loi
ve cam » ve cham, ve cac, va cam

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 hoi) OR (co hoi)). hieu ve cam duc gia thanh di ((dua tren) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang ((cao hoi) OR (co hoi)). hieu ve cam duc gia thanh di ((dua tren) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang ((cao hoi) OR (co hoi)). hieu ve cam duc gia thanh di ((dua tren) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang ((cao hoi) OR (co hoi)). hieu ve cam duc gia thanh di ((dua tren) or (cuu tre))*.