Perhaps you should try some spelling variations:
hien cac » thien cac, vien cac, hieu cac
tu sach » thu sach, su sach, te sach
ty nang » ty xang, ty hang, ly nang
hien ca » hien cau, hien cua, hieu ca
giao va » gia va, giai va, gian va
va dinh » van dinh, va kinh, va tinh
dinh va » dinh van, dinh ve, tinh va
cua tre » cua te, cuu tre, cua triet
va cua » va chua, via cua, ca cua

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 ((ty nang) OR (ky nang)) xa hoi. hieu ((hien ca) or (hien cac)) giao va dinh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ty nang) OR (ky nang)) xa hoi. hieu ((hien ca) OR (hien cac)) giao va dinh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ty nang) OR (ky nang)) xa hoi. hieu ((hien ca) or (hien cac)) giao va dinh va cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ty nang) OR (ky nang)) xa hoi. hieu ((hien ca) or (hien cac)) giao va dinh va cua tre*.