Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien cac » vien bach, vien dai, vien da
tu sach » thu sach, su sach, te sach
va danh » va dan, va hanh, dia danh
bat cua » ban cua, mat cua, bai cua
va dinh » van dinh, va kinh, va tinh
cac luc » cau luc, coc luc, cac nuoc
ky dang » ky danh
cua tre » cua te, cuu tre, cua triet

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