Perhaps you should try some spelling variations:
pham thuc » phap thuc, pham chuc, nham thuc
sang tao » hang tai
hanh tai » thanh tai, hang tai, han tai
dan hanh » dang hanh, dan khanh, dan thanh
thuc dan » thuc hanh, hoc dan, thuc vat
va triet » va thiet, va trien, ve triet
sach ky » sac ky, sach y, sach kem
sang ma » tang ma, nang ma, mang may
hieu ve » hieu va, hieu van
ve pham » vi pham, v pham, ve phan
sach ty » sach y, sach tu, sach thu
tai va » thai va, mai va, tri va

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 (sach ty)) ((sang ma) OR (sang tao)) hoi. hieu ve pham thuc dan hanh tai va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((sach ky) OR (sach ty)) ((sang ma) OR (sang tao)) hoi. hieu ve pham thuc dan hanh tai va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((sach ky) or (sach ty)) ((sang ma) OR (sang tao)) hoi. hieu ve pham thuc dan hanh tai va triet".
• Adding a wildcard symbol may retrieve word variants: doc ((sach ky) or (sach ty)) ((sang ma) OR (sang tao)) hoi. hieu ve pham thuc dan hanh tai va triet*.