Perhaps you should try some spelling variations:
pham thuc » phap thuc, pham chuc, nham thuc
su triet » su viet, su tien, ve triet
sach ty » sach y, sach tu, sach thu
sach ky » sach y, sach kem, sach hay
hieu vi » hieu voi, hieu va, hieu ve
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
hanh va » hang va, hanh vi
nang ma » tang ma, sang ma, nang cao
sac ky » cac ky, sai ky
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc ((((sach ky) OR (sac ky))) or (sach ty)) nang ma hoi. hieu vi pham thuc va hanh va su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((((sach ky) OR (sac ky))) OR (sach ty)) nang ma hoi. hieu vi pham thuc va hanh va su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((((sach ky) OR (sac ky))) or (sach ty)) nang ma hoi. hieu vi pham thuc va hanh va su triet".
• Adding a wildcard symbol may retrieve word variants: doc ((((sach ky) OR (sac ky))) or (sach ty)) nang ma hoi. hieu vi pham thuc va hanh va su triet*.