Perhaps you should try some spelling variations:
thuat sac » thuat sach, thuat san, thuat tac
van hanh » van thanh, ban hanh, van anh
luu van » cuu van, luan van, luu hanh
cam luu » tam luu
hieu ve » hieu va, hieu van
lang xa » lang ha, dang xay, lang van
mang xa » mang may, dang xay, mang cua
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky
vi cua » vai cua, di cua

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 ((mang xa) or (lang xa)) hoi. ((hieu ve) or (lieu va)) cam luu van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat sac ky ((mang xa) OR (lang xa)) hoi. ((hieu ve) OR (lieu va)) cam luu van hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: thuat sac ky ((mang xa) or (lang xa)) hoi. ((hieu ve) or (lieu va)) cam luu van hanh vi cua tre*.