Perhaps you should try some spelling variations:
thanh trinh » hanh trinh, thanh tinh, thanh binh
thanh tri » thanh tra, thanh tai, chinh tri
hieu van » hieu va, thien van, lieu va
dang xay » dang van, van xay
duc van » duc va, duc tan, duc manh
cua tre » cua te, cuu tre, cua triet
nam duc » nam duoc, pham duc, nam thuc
xay hoi » xa hoi, tay hoi, cay phoi
ky dang » ky nang, ky danh
su dai » sau dai, si dai, su tai
su sai » su tai, su hai, su mai

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((su sai) OR (su dai)) ky dang xay hoi. hieu van nam duc van ((thanh tri) or (thanh trinh)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sai) OR (su dai)) ky dang xay hoi. hieu van nam duc van ((thanh tri) OR (thanh trinh)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sai) OR (su dai)) ky dang xay hoi. hieu van nam duc van ((thanh tri) or (thanh trinh)) cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sai) OR (su dai)) ky dang xay hoi. hieu van nam duc van ((thanh tri) or (thanh trinh)) cua tre*.