Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
van hanh » van thanh, ban hanh, van anh
sach ty » sach y, sach tu, sach thu
nang ma » tang ma, sang ma, nang cao
sach ky » sac ky, sach y, sach kem
hieu ve » hieu va, hieu van
va hanh » va thanh, va danh, ban hanh
ma hoi » mai hoi, xa hoi, ma hoa
ve dam » ven dam, ke dam, va dam
dam tu » nam tu, cam tu, tam tu

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