Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
va triet » va thiet, va trien, ve triet
hanh tai » thanh tai, hang tai, han tai
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
vien cac » vien bach, vien dai, vien da
va hanh » van hanh, va thanh, va danh
tu sach » thu sach, su sach, te sach
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
vu sach » vu bach, su sach, vu khach
tai va » thai va, mai va, tri va

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (vu sach)) ky ((nang xa) or (nang ma)) hoi. hieu vien cac nuoc va hanh tai va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (vu sach)) ky ((nang xa) OR (nang ma)) hoi. hieu vien cac nuoc va hanh tai va triet.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (vu sach)) ky ((nang xa) or (nang ma)) hoi. hieu vien cac nuoc va hanh tai va triet*.