Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
danh vai » danh sai, danh va, doanh van
dang xay » dang van, van xay
co sach » bo sach, cuon sach
vai cua » dai cua, hai cua, lai cua
va danh » va dinh, va dan, va hanh
ky dang » ky nang, ky danh
xay hoi » xa hoi, tay hoi, cay phoi
cua tre » cua te, cuu tre, cua triet
va cau » van cau, va dau, va cao
luc va » duc va, tuc va, loc va

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((co sach) or (hoc sach)) ky dang xay hoi. hieu ((va cau) OR (va cac)) luc va danh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((co sach) OR (hoc sach)) ky dang xay hoi. hieu ((va cau) OR (va cac)) luc va danh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((co sach) or (hoc sach)) ky dang xay hoi. hieu ((va cau) OR (va cac)) luc va danh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((co sach) or (hoc sach)) ky dang xay hoi. hieu ((va cau) OR (va cac)) luc va danh vai cua tre*.