Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thanh dai » thanh hai, thanh tai, thanh dat
cua triet » cua viet, su triet, va triet
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
cac dac » cac dan, cac dai, cac tac
cac bac » cac bai, cac ban, cac cach
y nang » ky nang, ly nang, v nang

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach y nang ((xa hoi) or (x ho)). hieu van ((cac dac) OR (cac bac)) ban thanh dai cua triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y nang ((xa hoi) OR (x ho)). hieu van ((cac dac) OR (cac bac)) ban thanh dai cua triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach y nang ((xa hoi) or (x ho)). hieu van ((cac dac) OR (cac bac)) ban thanh dai cua triet".
• Adding a wildcard symbol may retrieve word variants: thu sach y nang ((xa hoi) or (x ho)). hieu van ((cac dac) OR (cac bac)) ban thanh dai cua triet*.