Perhaps you should try some spelling variations:
thuat sac » thuat sach, thuat san, thuat tac
sieu viet » su viet, dien viet, bien viet
van thanh » ban thanh, van tuan
viet cac » vien cac, viet ca, viet bac
sac ky » cac ky, sai ky
cac vo » cac co, cac vi, cac bo
via va » via van, vua va, dia va
gia va » gia ba
x hoi » xa hoi, o hoi, 5 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 ((x hoi) or (x ho)). sieu viet cac vo van thanh ((via va) OR (gia va)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat sac ky nang ((x hoi) OR (x ho)). sieu viet cac vo van thanh ((via va) OR (gia va)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat sac ky nang ((x hoi) or (x ho)). sieu viet cac vo van thanh ((via va) OR (gia va)) triet".
• Adding a wildcard symbol may retrieve word variants: thuat sac ky nang ((x hoi) or (x ho)). sieu viet cac vo van thanh ((via va) OR (gia va)) triet*.