Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cam truc » nam truc, lam truoc, nam truoc
cuu tre » cua tre, cau tren, cau treo
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
sac ky » cac ky, sai ky
va don » va dong, va doc, va do
vi cuu » vi luu, vinh cuu
te sac » te sach, te cac, te san

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sac ky ((nang xa) or (nang ma)) hoi. hieu van ((cam truc) OR (cau truc)) va don vi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sac ky ((nang xa) OR (nang ma)) hoi. hieu van ((cam truc) OR (cau truc)) va don vi cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sac ky ((nang xa) or (nang ma)) hoi. hieu van ((cam truc) OR (cau truc)) va don vi cuu tre".
• Adding a wildcard symbol may retrieve word variants: te sac ky ((nang xa) or (nang ma)) hoi. hieu van ((cam truc) OR (cau truc)) va don vi cuu tre*.