Perhaps you should try some spelling variations:
thien van » thi van
doc sach » hoc sach, toc sach, nuoc sach
luoc van » luoc can, luoc va, luc van
cua viet » ca viet, hoa viet, cua vat
van cam » van nam, van lam, van cau
loc van » hoc van, lo van, loc va
hang di » hang doi, hang vi, hang dien
y nang » ky nang, ly nang, v nang
di cua » dai cua, doi cua, de cua
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: doc sach y nang ((x hoi) or (x ho)). thien van cam ((loc van) OR (luoc van)) hang di cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach y nang ((x hoi) OR (x ho)). thien van cam ((loc van) OR (luoc van)) hang di cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach y nang ((x hoi) or (x ho)). thien van cam ((loc van) OR (luoc van)) hang di cua viet".
• Adding a wildcard symbol may retrieve word variants: doc sach y nang ((x hoi) or (x ho)). thien van cam ((loc van) OR (luoc van)) hang di cua viet*.