Perhaps you should try some spelling variations:
thuat sac » thuat sach, thuat san, thuat tac
lam truoc » lam thuoc, nam truoc, lam truong
truoc va » truc va, thuoc va, truong va
hanh voi » hanh noi, hanh moi, lanh voi
nang xa » lang xa, nang ma, mang xa
hieu va » lieu va, hieu qua
sac ky » cac ky, sai ky
va lam » van lam, va lap

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 xa) or (nang x)) hoi. hieu va lam truoc va ((hanh voi) OR (hanh vi)) hoa viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat sac ky ((nang xa) OR (nang x)) hoi. hieu va lam truoc va ((hanh voi) OR (hanh vi)) hoa viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat sac ky ((nang xa) or (nang x)) hoi. hieu va lam truoc va ((hanh voi) OR (hanh vi)) hoa viet".
• Adding a wildcard symbol may retrieve word variants: thuat sac ky ((nang xa) or (nang x)) hoi. hieu va lam truoc va ((hanh voi) OR (hanh vi)) hoa viet*.