Perhaps you should try some spelling variations:
sach hoi » sach doi, cach thoi, hoach hoi
sach moi » sach doi, bach mai, sach bai
manh xay » nganh xay, van xay, dang xay
sach lo » sach dao, sach doi, sach bao
xay hoi » xa hoi, tay hoi, cay phoi
hieu va » lieu va, hieu qua
va giao » van giao, va giai, va gia
va hanh » van hanh, va thanh, va danh
vi va » vi van, vai va, vu 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) OR (sach moi))) or (sach hoi)) manh xay hoi. hieu va giao duc va hanh vi va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((((sach lo) OR (sach moi))) OR (sach hoi)) manh xay hoi. hieu va giao duc va hanh vi va thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((((sach lo) OR (sach moi))) or (sach hoi)) manh xay hoi. hieu va giao duc va hanh vi va thiet".
• Adding a wildcard symbol may retrieve word variants: su ((((sach lo) OR (sach moi))) or (sach hoi)) manh xay hoi. hieu va giao duc va hanh vi va thiet*.