Perhaps you should try some spelling variations:
hanh tinh » hanh trinh, nhanh tinh, thanh tinh
tinh che » tinh cho, tinh he, dinh che
che duoc » che thuoc, che do, te duoc
duoc hoc » quoc hoi
tu sach » thu sach, su sach, te sach
sach te » sach tet, sach de, sach tu
te nghe » ve nghe, re nghe, tu nghe
nghe vi » nghe va, nghe noi
du hanh » dieu hanh, duy khanh, luu hanh
vi hoc » li hoc, va hoc

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 te nghe vi hoc ) or ( du hanh tinh che duoc hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach te nghe vi hoc ) OR ( du hanh tinh che duoc hoc )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach te nghe vi hoc ) or ( du hanh tinh che duoc hoc ))*.