Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
cay phoi » cap phoi, tay hoi, cay cho
chu tren » cu tren, cau tren, chu trang
xay hoi » xa hoi, tay hoi, gay thoi
ky dang » ky nang, ky danh
sach ky » sac ky, sach y, sach ty
nam duc » nam duoc, pham duc, nam thuc
va danh » va dinh, va dan, dia danh
va hanh » van hanh, va thanh, ban hanh
qua nam » quan nam, cua nam, quang nam
ve chu » ve cau, va chu, ve che

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sach ky dang ((xay hoi) OR (cay phoi)). hieu qua nam duc ((va danh) or (va hanh)) ve chu tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ky dang ((xay hoi) OR (cay phoi)). hieu qua nam duc ((va danh) OR (va hanh)) ve chu tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach ky dang ((xay hoi) OR (cay phoi)). hieu qua nam duc ((va danh) or (va hanh)) ve chu tren".
• Adding a wildcard symbol may retrieve word variants: hoc sach ky dang ((xay hoi) OR (cay phoi)). hieu qua nam duc ((va danh) or (va hanh)) ve chu tren*.