Perhaps you should try some spelling variations:
cac trung » cac truong, bac trung, cao trung
dac trung » duc trung, cac truong, tai trung
toc sach » hoc sach, doc sach, thuoc sach
ban hanh » ban hang
luu tre » luu tru, cuu tre, luy tre
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
cho hoc » co hoc, khoa hoc
cao hoi » cau hoi, co hoi, cao hoc
vi luu » vi lua

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ky nang ((cao hoi) or (cho hoc)). hieu ve ((cac trung) OR (dac trung)) ban hanh vi luu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky nang ((cao hoi) OR (cho hoc)). hieu ve ((cac trung) OR (dac trung)) ban hanh vi luu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky nang ((cao hoi) or (cho hoc)). hieu ve ((cac trung) OR (dac trung)) ban hanh vi luu tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ky nang ((cao hoi) or (cho hoc)). hieu ve ((cac trung) OR (dac trung)) ban hanh vi luu tre*.