Perhaps you should try some spelling variations:
cua triet » su triet, va triet
thu sach » tu sach, thuat sach, thuoc sach
cham duc » pham duc, cham soc, pham duy
hanh tai » thanh tai, hang tai, han tai
van hanh » van thanh, ban hanh, van anh
cua viet » ca viet, hoa viet, cua vat
hieu vu » hieu va, hieu ve, hieu su
sach ky » sac ky, sach y, sach ty
duc van » duc va, duc tan, duc manh
nang ma » tang ma, sang ma, nang cao
vu cham » va cham, vu kham, tu cham

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