Perhaps you should try some spelling variations:
cac trung » cac truong, bac trung, cao trung
dac trung » duc trung, cac truong, tai trung
doc sach » hoc sach, toc sach, nuoc 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: doc 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: doc 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: doc sach ky nang ((cao hoi) or (cho hoc)). hieu ve ((cac trung) or (dac trung)) ban hanh vi luu tre*.