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
sach te » sach tet, sach tu, sach ty
sach de » cach de, sach dao, sach dat
nghe vi » nghe va, nghe noi
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) or (sach de)) nghe vi hoc ) or ( dieu hanh tinh che duoc hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu ((sach te) OR (sach de)) nghe vi hoc ) OR ( dieu hanh tinh che duoc hoc )).
• Adding a wildcard symbol may retrieve word variants: (( tu ((sach te) or (sach de)) nghe vi hoc ) or ( dieu hanh tinh che duoc hoc ))*.