Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
van hanh » van thanh, ban hanh, van anh
duc van » duc va, duc tan, duc manh
hac duc » hoc duc, ha duc, thach duc
van hac » van hoc, van ha, van hai
te sach » toc sach
ty hang » ly hang, ty xang, thi hang
ty nang » ky nang, ty xang, ly nang
cua co » cua bo, cua cong
cua su » qua su

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ((ty nang) OR (ty hang)) xa hoi. hieu van hac duc van hanh vi ((cua co) or (cua su))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((ty nang) OR (ty hang)) xa hoi. hieu van hac duc van hanh vi ((cua co) OR (cua su)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((ty nang) OR (ty hang)) xa hoi. hieu van hac duc van hanh vi ((cua co) or (cua su))".
• Adding a wildcard symbol may retrieve word variants: te sach ((ty nang) OR (ty hang)) xa hoi. hieu van hac duc van hanh vi ((cua co) or (cua su))*.