Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hanh tai » thanh tai, hang tai, han tai
van hanh » van thanh, ban hanh, van anh
cham duc » pham duc, pham duy, phan duc
va triet » va thiet, va trien, ve triet
hieu vu » hieu va, hieu ve, hieu su
nang ma » tang ma, sang ma, nang cao
tai va » thai va, mai va, tri va

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

• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach nha ((nang ma) OR (nang x)) hoi. hieu vu ((cham duc) OR (cham soc)) van hanh tai va triet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach nha ((nang ma) or (nang x)) hoi. hieu vu ((cham duc) OR (cham soc)) van hanh tai va triet~".
• Adding a wildcard symbol may retrieve word variants: thu sach nha ((nang ma) or (nang x)) hoi. hieu vu ((cham duc) OR (cham soc)) van hanh tai va triet*.