Perhaps you should try some spelling variations:
mai viet » thi viet
hieu van » hieu va, thien van, lieu va
van hanh » van thanh, ban hanh, van anh
hanh di » hanh vi, hanh de, hang di
duc van » duc va, duc tan, duc manh
cam duc » cam xuc, cao duc, pham duc
tu cach » tu cac
van cam » van nam, van lam, van cau
su sach » so sach, vu sach
y nang » ky nang, ly nang, v nang
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu cach) or (su sach)) y nang x hoi. hieu van cam duc van hanh di ((cua vat) or (mai viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu cach) OR (su sach)) y nang x hoi. hieu van cam duc van hanh di ((cua vat) OR (mai viet)).
• Adding a wildcard symbol may retrieve word variants: ((tu cach) or (su sach)) y nang x hoi. hieu van cam duc van hanh di ((cua vat) or (mai viet))*.