Perhaps you should try some spelling variations:
dang than » dang thanh, sang than, dang tran
cac nuoc » hoc nuoc, dat nuoc, cua nuoc
than cua » nhan cua, thai cua, ban cua
cap nuoc » dat nuoc
hieu van » hieu va, thien van, lieu va
va dang » van dang, va nang, va lang
sach ky » sac ky, sach ty, sach kem
nang xa » nang x, lang xa, nang ma
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) OR (sach y)) nang xa hoi. hieu van ((cac nuoc) or (cap nuoc)) va dang than cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat ((sach ky) OR (sach y)) nang xa hoi. hieu van ((cac nuoc) OR (cap nuoc)) va dang than cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat ((sach ky) OR (sach y)) nang xa hoi. hieu van ((cac nuoc) or (cap nuoc)) va dang than cua te".
• Adding a wildcard symbol may retrieve word variants: thuat ((sach ky) OR (sach y)) nang xa hoi. hieu van ((cac nuoc) or (cap nuoc)) va dang than cua te*.