Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
hanh di » hanh vi, hanh de, hang di
sac van » cac van, san van, sat van
tu cham » toc cham, thi cham
ve cham » va cham, ve chat, vu cham
tay hoi » tay ho, tao hoi, tay thai
xay hoi » xa hoi, cay phoi, gay thoi
ty dang » ty xang, ky dang, ty hang
cua tre » cua te, cuu tre, cua triet
di cua » dai cua, doi cua, de cua

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 ty dang ((xay hoi) OR (tay hoi)). hieu ((ve cham) or (tu cham)) sac van hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty dang ((xay hoi) OR (tay hoi)). hieu ((ve cham) OR (tu cham)) sac van hanh di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty dang ((xay hoi) OR (tay hoi)). hieu ((ve cham) or (tu cham)) sac van hanh di cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ty dang ((xay hoi) OR (tay hoi)). hieu ((ve cham) or (tu cham)) sac van hanh di cua tre*.