Perhaps you should try some spelling variations:
su sach » so sach, vu sach
sach lo » sach dao, sach doi, sach hoi
lo xang » le xang
xang xa » lang xa, mang xa, ang xa
hieu va » lieu va, hieu qua
va giao » van giao, va giai, va gia
va hanh » van hanh, va thanh, va danh
vai va » mai va, dai va, lai va
hai va » hai van, thai va, hoi va
thiet » thieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach lo xang xa hoi. hieu va giao duc va hanh ((vai va) OR (hai va)) thiet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach lo xang xa hoi. hieu va giao duc va hanh ((vai va) OR (hai va)) thiet".
• Adding a wildcard symbol may retrieve word variants: su sach lo xang xa hoi. hieu va giao duc va hanh ((vai va) OR (hai va)) thiet*.