Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
toc sac » toc sach, hoc sach, doc sach
duc van » duc va, duc tan, duc manh
hieu va » lieu va, hieu qua
hieu ve » hieu van
dang ha » dong ha, dung ha, lang ha
ky dang » ky nang, ky danh
ha hoi » hoa hoi, ha noi, xa hoi
vi cua » vai cua, di cua
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((toc sac) or (toc san)) ky dang ha hoi. ((hieu ve) OR (hieu va)) pham duc van hanh vi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sac) OR (toc san)) ky dang ha hoi. ((hieu ve) OR (hieu va)) pham duc van hanh vi cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sac) or (toc san)) ky dang ha hoi. ((hieu ve) OR (hieu va)) pham duc van hanh vi cua te".
• Adding a wildcard symbol may retrieve word variants: ((toc sac) or (toc san)) ky dang ha hoi. ((hieu ve) OR (hieu va)) pham duc van hanh vi cua te*.