Perhaps you should try some spelling variations:
luan phan » luan van, luan hoan
hieu luan » hieu luat, hieu quan, tieu luan
duc manh » suc manh, duc anh, duc minh
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
duc van » duc va, duc tan, duc phan
x hoi » xa hoi, o hoi, x ho
vi su » ve su, ki su, oi su

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

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