Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
cham sac » cham soc, pham sach, cap sac
hieu su » hieu sau, tieu su, hieu so
hanh di » hanh vi, hanh de, hang di
sac van » cac van, san van, sat van
su cham » su pham, tu cham, vu cham
su sach » so sach, vu sach
ty hang » ly hang, thi hang, thu hang
ty lang » tay lang, tu lang, tai lang
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 lang) or (ty hang))) or (ty xang)) xa hoi. hieu su cham sac van hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((((ty lang) OR (ty hang))) OR (ty xang)) xa hoi. hieu su cham sac van hanh di cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach ((((ty lang) or (ty hang))) or (ty xang)) xa hoi. hieu su cham sac van hanh di cua tre*.