Perhaps you should try some spelling variations:
luan phan » luan van
luan hoan » luan van
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
ty nang » ty xang, ty hang, ly nang
duc van » duc va, duc tan, duc manh
su viet » so viet
x hoi » xa hoi, o hoi, x ho
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 ((ty nang) or (ky nang)) x hoi. hieu ((luan phan) OR (luan hoan)) duc van hanh vi su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ty nang) OR (ky nang)) x hoi. hieu ((luan phan) OR (luan hoan)) duc van hanh vi su viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ty nang) or (ky nang)) x hoi. hieu ((luan phan) OR (luan hoan)) duc van hanh vi su viet".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ty nang) or (ky nang)) x hoi. hieu ((luan phan) OR (luan hoan)) duc van hanh vi su viet*.