Perhaps you should try some spelling variations:
nuoc sach » nguoi sach, hoc sach, cuoc cach
thanh tai » thanh hai, thanh toan, thanh san
hieu cua » hieu qua, dieu cua, bieu cua
ty hang » ly hang, ty xang, thi hang
ty nang » ky nang, ty xang, ly nang
ca viet » va viet, co viet, hoa viet
cac lo » cac lop, cac co, cac bo
lo va » lo van, lao va, ly va

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

• Performing a fuzzy search may retrieve terms with similar spellings: nuoc sach ((ty nang) or (ty hang)) xa hoi. hieu cua cac lo va ((thanh tai) OR (doanh tai)) ca viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: nuoc sach ((ty nang) OR (ty hang)) xa hoi. hieu cua cac lo va ((thanh tai) OR (doanh tai)) ca viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "nuoc sach ((ty nang) or (ty hang)) xa hoi. hieu cua cac lo va ((thanh tai) OR (doanh tai)) ca viet".
• Adding a wildcard symbol may retrieve word variants: nuoc sach ((ty nang) or (ty hang)) xa hoi. hieu cua cac lo va ((thanh tai) OR (doanh tai)) ca viet*.