Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
cham duc » pham duc, cham soc, pham duy
tu sach » thu sach, su sach, te sach
vu cham » va cham, vu kham, tu cham
lam cua » nam cua, lam chat
va hanh » va thanh, va danh, ban hanh
hieu vu » hieu va, hieu ve, hieu su
sach ty » sach y, sach tu, sach thu
ty tang » tay tang, ty xang, ty hang
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, 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: tu sach ty tang ((ma hoi) OR (ma hoa)). 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: tu sach ty tang ((ma hoi) OR (ma hoa)). 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: "tu sach ty tang ((ma hoi) OR (ma hoa)). hieu vu cham duc ((va hanh) or (van hanh)) lam cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ty tang ((ma hoi) OR (ma hoa)). hieu vu cham duc ((va hanh) or (van hanh)) lam cua tre*.