Perhaps you should try some spelling variations:
cuu thuc » cuu tac
hanh tue » hanh tu, hanh tuyen, hanh theo
dan hanh » dang hanh, dan khanh, dan thanh
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
nang xa » lang xa, nang ma, mang xa
tue cua » te cua
sach ky » sac ky, sach y, sach ty
cu thuc » co thuc, cu thu, tu thuc
cua tu » cua tuc, cua su, cua cu

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky ((nang xa) or (nang x)) hoi. hieu van ((cu thuc) OR (cuu thuc)) dan hanh tue cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang xa) OR (nang x)) hoi. hieu van ((cu thuc) OR (cuu thuc)) dan hanh tue cua tu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang xa) or (nang x)) hoi. hieu van ((cu thuc) OR (cuu thuc)) dan hanh tue cua tu".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang xa) or (nang x)) hoi. hieu van ((cu thuc) OR (cuu thuc)) dan hanh tue cua tu*.