Perhaps you should try some spelling variations:
hieu quan » lieu quan, thien quan, lien quan
thu sach » tu sach, thuat sach, thuoc sach
cua viet » ca viet, hoa viet, cua vat
su sach » so sach, vu sach
va hanh » van hanh, va thanh, va danh
y nang » ky nang, ly nang, v nang
nang o » nang co, nang ho, nang ro
xuc va » duc va, tuc va, luc va
vi cua » vai cua, di cua
o hoi » co hoi, o hoc, o hai

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu sach) or (su sach)) y nang o hoi. ((hieu quan) or (hieu qua)) cam xuc va hanh vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (su sach)) y nang o hoi. ((hieu quan) OR (hieu qua)) cam xuc va hanh vi cua viet.
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (su sach)) y nang o hoi. ((hieu quan) or (hieu qua)) cam xuc va hanh vi cua viet*.