Perhaps you should try some spelling variations:
hieu quan » lieu quan, thien quan, lien quan
vien quan » lien quan, van quan, tin quan
hanh vinh » thanh vinh, khanh vinh, hanh tinh
vinh cuu » dinh cuu, sinh cua, dinh cu
tu sach » thu sach, su sach, te sach
va hanh » van hanh, va thanh, va danh
cuu tre » cua tre, cau tren, cau treo
y nang » ky nang, ly nang, v nang
thu va » thuc va, thue va, tu va
x hoi » xa hoi, o hoi, x ho

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 x hoi. ((((hieu quan) or (vien quan))) or (hieu qua)) nam thu va hanh vinh cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang x hoi. ((((hieu quan) OR (vien quan))) OR (hieu qua)) nam thu va hanh vinh cuu tre.
• Adding a wildcard symbol may retrieve word variants: tu sach y nang x hoi. ((((hieu quan) or (vien quan))) or (hieu qua)) nam thu va hanh vinh cuu tre*.