Perhaps you should try some spelling variations:
pham thuc » phap thuc, pham chuc, nham thuc
su triet » su viet, su tien, ve triet
vanh dai » van dai, vanh tai, lanh dao
cham tuc » nham thuc, tham thuc, cham soc
va vanh » va van, va danh, va hanh
hieu ve » hieu va, hieu van
te sach » toc sach
tang ma » mang may, tang van
nang ma » sang ma, nang cao, mang may
sach 2 » sach y
dai su » dai sua, dai so, dan su

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach 2 ((nang ma) or (tang ma)) hoi. hieu ve ((cham tuc) OR (pham thuc)) va vanh dai su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach 2 ((nang ma) OR (tang ma)) hoi. hieu ve ((cham tuc) OR (pham thuc)) va vanh dai su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach 2 ((nang ma) or (tang ma)) hoi. hieu ve ((cham tuc) OR (pham thuc)) va vanh dai su triet".
• Adding a wildcard symbol may retrieve word variants: te sach 2 ((nang ma) or (tang ma)) hoi. hieu ve ((cham tuc) OR (pham thuc)) va vanh dai su triet*.