Perhaps you should try some spelling variations:
thuat sac » thuat sach, thuat san, thuat tac
hieu van » hieu va, thien van, lieu va
nam duoc » nam thuoc, da duoc, dat duoc
duoc may » duoc ma, duoc ly, hoc may
tinh da » tinh gia, tinh lao, tinh nam
tinh va » tich va, trinh van, trinh vat
ca tren » cau tren, cu tren, la tren
sac ky » cac ky, sai ky
ma hoi » mai hoi, ma hoa, me hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuat sac ky nang ((ma hoi) or (xa hoi)). hieu van nam duoc may ((tinh da) OR (tinh va)) ca tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat sac ky nang ((ma hoi) OR (xa hoi)). hieu van nam duoc may ((tinh da) OR (tinh va)) ca tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat sac ky nang ((ma hoi) or (xa hoi)). hieu van nam duoc may ((tinh da) OR (tinh va)) ca tren".
• Adding a wildcard symbol may retrieve word variants: thuat sac ky nang ((ma hoi) or (xa hoi)). hieu van nam duoc may ((tinh da) OR (tinh va)) ca tren*.