Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
va danh » va dinh, va dan, va hanh
hieu va » lieu va, hieu qua
lam loc » lam duoc, lam ngoc
v nang » va nang, vu nang, van nang
va lam » van lam, va lap
y nang » ky nang, ly nang, may nang
loc va » hoc va, luc va
di cu » di cau, di cua, da cu
di du » li du

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 ((y nang) or (v nang)) xa hoi. hieu va lam loc va danh ((di cu) OR (di du)) tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((y nang) OR (v nang)) xa hoi. hieu va lam loc va danh ((di cu) OR (di du)) tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((y nang) or (v nang)) xa hoi. hieu va lam loc va danh ((di cu) OR (di du)) tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ((y nang) or (v nang)) xa hoi. hieu va lam loc va danh ((di cu) OR (di du)) tren*.