Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
sach duoc » sach nuoc, sach dao, sach dung
hanh tai » thanh tai, hang tai, han tai
hieu van » hieu va, thien van, lieu va
tai cua » thai cua, tai cuc, tri cua
va hanh » van hanh, va thanh, va danh
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, mang may
bac tuc » bac tu, bach tuoc, bac thua

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