Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
van lam » van nam
xuc va » tuc va, luc va, xac va
x hoi » xa hoi, o hoi, x ho
vi su » va su, ve su, oi su
ki su » ky 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 ky nang x hoi. hieu van lam ((xuc va) or (duc va)) hanh ((vi su) OR (ki su)) tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. hieu van lam ((xuc va) OR (duc va)) hanh ((vi su) OR (ki su)) tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x hoi. hieu van lam ((xuc va) or (duc va)) hanh ((vi su) OR (ki su)) tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. hieu van lam ((xuc va) or (duc va)) hanh ((vi su) OR (ki su)) tren*.