Perhaps you should try some spelling variations:
thuat bang » thuat ban, thuat mang, thuat nang
hieu van » hieu va, thien van, lieu va
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
dang tai » dang thai, dung tai, hang tai
bang ky » dang ky, ban ky, tang ky
nang ma » tang ma, sang ma, mang may
van cac » van hac, van cau, van bac
va dang » van dang, va nang, va lang
cuc te » cuc thue, cuc tieu
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 bang ky ((nang ma) or (nang cao)) hoi. hieu van cac nuoc va dang tai ((cuc te) OR (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat bang ky ((nang ma) OR (nang cao)) hoi. hieu van cac nuoc va dang tai ((cuc te) OR (cua te)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat bang ky ((nang ma) or (nang cao)) hoi. hieu van cac nuoc va dang tai ((cuc te) OR (cua te))".
• Adding a wildcard symbol may retrieve word variants: thuat bang ky ((nang ma) or (nang cao)) hoi. hieu van cac nuoc va dang tai ((cuc te) OR (cua te))*.