Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
dang khoi » dung khoa, hang khoa
dang khai » dang hai, quang khai, dang thi
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
hieu van » hieu va, thien van, lieu va
van cac » van hac, van cau, van bac
nang xa » lang xa, nang ma, mang xa
sach ky » sac ky, sach y, sach ty
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuat sach ky ((nang xa) or (nang x)) hoi. hieu van cac nuoc va ((dang khai) OR (dang khoi)) cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat sach ky ((nang xa) OR (nang x)) hoi. hieu van cac nuoc va ((dang khai) OR (dang khoi)) cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat sach ky ((nang xa) or (nang x)) hoi. hieu van cac nuoc va ((dang khai) OR (dang khoi)) cua te".
• Adding a wildcard symbol may retrieve word variants: thuat sach ky ((nang xa) or (nang x)) hoi. hieu van cac nuoc va ((dang khai) OR (dang khoi)) cua te*.