Perhaps you should try some spelling variations:
hieu luan » hieu quan, tieu luan, hieu quang
hieu luat » hieu qua
van hanh » van thanh, ban hanh, van anh
phan duc » pham duc, phan tu, phan dau
tu sach » thu sach, su sach, tu cach
duc van » duc va, duc tan, duc manh
su viet » so viet
nang xa » nang x, lang xa, nang ma
ty nang » ky nang, ty xang, ty hang
te sach » toc sach
vi su » va su, ve su, ki su

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 (te sach)) ty nang xa hoi. ((hieu luan) or (hieu luat)) phan duc van hanh vi su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (te sach)) ty nang xa hoi. ((hieu luan) OR (hieu luat)) phan duc van hanh vi su viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (te sach)) ty nang xa hoi. ((hieu luan) or (hieu luat)) phan duc van hanh vi su viet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (te sach)) ty nang xa hoi. ((hieu luan) or (hieu luat)) phan duc van hanh vi su viet*.