Perhaps you should try some spelling variations:
thanh dat » thanh san, thanh hai, thanh van
hieu van » hieu va, thien van, lieu va
va thanh » gia thanh, ban thanh, va tinh
ve triet » va trien, su triet
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
van cau » van dau, van hau, van chat
cau duc » cao duc, cau luc, chu duc
dat ve » dat va, dat de, dat vi
o hoa » do hoa, so hoa, o ha
o hai » co hai, so hai, o lai

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 ky nang ((o hoa) or (o hai)). hieu van cau duc va thanh dat ve triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((o hoa) OR (o hai)). hieu van cau duc va thanh dat ve triet.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((o hoa) or (o hai)). hieu van cau duc va thanh dat ve triet*.