Perhaps you should try some spelling variations:
thanh lap » thanh san, phan lap, thanh hai
van tham » van thanh, van tuan, van chat
tham duc » pham duc, tham du, than duc
hanh lai » hanh lam, hanh tai, thanh loi
hieu van » hieu va, thien van, lieu va
duc ban » duc tan, duc van, dua ban
su sach » so sach, vu sach
ki nang » ky nang
sach ki » sach kinh, sach bai, sach kem
o hoi » co hoi, o hoc, o hai

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ki nang ((o hoi) or (xa hoi)). hieu van tham duc ban ((hanh lai) OR (thanh lap)) cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ki nang ((o hoi) OR (xa hoi)). hieu van tham duc ban ((hanh lai) OR (thanh lap)) cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ki nang ((o hoi) or (xa hoi)). hieu van tham duc ban ((hanh lai) OR (thanh lap)) cua vat".
• Adding a wildcard symbol may retrieve word variants: su sach ki nang ((o hoi) or (xa hoi)). hieu van tham duc ban ((hanh lai) OR (thanh lap)) cua vat*.