Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
thanh dai » thanh hai, thanh tai, thanh dat
cua triet » su triet, va triet
cua viet » ca viet, hoa viet, cua vat
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
cac bac » cac bai, cac ban, cac cach
bac van » bach van, cac van, ban van
sach v » sach va, sach y, sach 2
v nang » va nang, vu nang, van nang
x hoi » o hoi, x ho, 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: tu sach v nang ((x hoi) or (xa hoi)). hieu va cac bac van thanh dai ((cua triet) OR (cua viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach v nang ((x hoi) OR (xa hoi)). hieu va cac bac van thanh dai ((cua triet) OR (cua viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach v nang ((x hoi) or (xa hoi)). hieu va cac bac van thanh dai ((cua triet) OR (cua viet))".
• Adding a wildcard symbol may retrieve word variants: tu sach v nang ((x hoi) or (xa hoi)). hieu va cac bac van thanh dai ((cua triet) OR (cua viet))*.