Perhaps you should try some spelling variations:
sach thu » sach thue, sach thieu, sach tham
sach ty » sach y, sach tu, xach tay
hieu va » lieu va, hieu qua
va pham » van pham, va phat, va phap
va danh » va dinh, va dan, dia danh
va hanh » van hanh, va thanh, ban hanh
cua tre » cua te, cuu tre, cua triet
vi cua » vai cua, di cua
x hoi » xa hoi, o hoi, x ho

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) OR (sach thu)) nang x hoi. hieu va pham duc ((va danh) or (va hanh)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sach thu)) nang x hoi. hieu va pham duc ((va danh) OR (va hanh)) vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ty) OR (sach thu)) nang x hoi. hieu va pham duc ((va danh) or (va hanh)) vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) OR (sach thu)) nang x hoi. hieu va pham duc ((va danh) or (va hanh)) vi cua tre*.