Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
thanh te » thanh ve, thanh de, thanh le
su sach » so sach, vu sach
hieu va » lieu va, hieu qua
va phan » van phan, va phat, va phap
luc van » luoc van, duc van, luc va
luu van » cuu van, luan van, luu hanh
te cua » tue cua, le cua, de cua
x hoi » xa hoi, o hoi, x ho

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (toc sach)) ky nang x hoi. hieu va phan ((luc van) OR (luu van)) thanh te cua vat~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (toc sach)) ky nang x hoi. hieu va phan ((luc van) OR (luu van)) thanh te cua vat~".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (toc sach)) ky nang x hoi. hieu va phan ((luc van) OR (luu van)) thanh te cua vat*.