Perhaps you should try some spelling variations:
toan hanh » toan thanh, toan anh, tran hanh
tan hanh » tan thanh, tang hanh, tran hanh
pham duy » pham duc
cua tre » cua te, cuu tre, cua triet
vu pham » su pham, vi pham, vu kham
hieu vu » hieu va, hieu ve, hieu su
dai hoi » dai hoc, dai hai, dai moi
sai ky » sac ky
ma hoi » mai hoi, xa hoi, ma hoa
vi cua » vai cua, di cua
tu sai » tu bai, tu san, tu cai

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sai ky nang ((ma hoi) or (dai hoi)). hieu vu pham duy ((tan hanh) OR (toan hanh)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sai ky nang ((ma hoi) OR (dai hoi)). hieu vu pham duy ((tan hanh) OR (toan hanh)) vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sai ky nang ((ma hoi) or (dai hoi)). hieu vu pham duy ((tan hanh) OR (toan hanh)) vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sai ky nang ((ma hoi) or (dai hoi)). hieu vu pham duy ((tan hanh) OR (toan hanh)) vi cua tre*.