Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
cham duc » pham duc, cham soc, pham duy
so sach » so sanh, bo sach, co sach
lam cua » nam cua, lam chat
va hanh » va thanh, va danh, ban hanh
vu cham » va cham, vu kham, tu cham
hieu vu » hieu va, hieu ve, hieu su
sach ty » sach y, sach tu, sach thu
mai hoi » mai khoi, dai hoi, lai hoi
ty tang » tay tang, ty xang, ty hang
cua tre » cua te, cuu tre, cua triet
ma hoi » xa hoi, ma hoa, me hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ty tang ((ma hoi) or (mai hoi)). hieu vu cham duc ((va hanh) OR (van hanh)) lam cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ty tang ((ma hoi) OR (mai hoi)). hieu vu cham duc ((va hanh) OR (van hanh)) lam cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ty tang ((ma hoi) or (mai hoi)). hieu vu cham duc ((va hanh) OR (van hanh)) lam cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach ty tang ((ma hoi) or (mai hoi)). hieu vu cham duc ((va hanh) OR (van hanh)) lam cua tre*.