Perhaps you should try some spelling variations:
thien van » thi van
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
van dang » van dong, van dung, van nang
sach ky » sac ky, sach y, sach kem
sach ty » sach y, sach tu, sach thu
nang xa » nang x, lang xa, nang ma
van cac » van hac, van cau, van bac
va dang » va nang, va lang, da dang
cuc te » cua te, cuc thue, cuc tieu

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 ty)) nang xa hoi. thien van cac nuoc ((va dang) or (van dang)) tai cuc te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat ((sach ky) OR (sach ty)) nang xa hoi. thien van cac nuoc ((va dang) OR (van dang)) tai cuc te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat ((sach ky) OR (sach ty)) nang xa hoi. thien van cac nuoc ((va dang) or (van dang)) tai cuc te".
• Adding a wildcard symbol may retrieve word variants: thuat ((sach ky) OR (sach ty)) nang xa hoi. thien van cac nuoc ((va dang) or (van dang)) tai cuc te*.