Perhaps you should try some spelling variations:
dang thanh » dong thanh, hoang thanh, quang thanh
dang hanh » ban hanh, dang van, dang hung
su triet » su viet, su tien, ve triet
sach ky » sac ky, sach ty, sach kem
hieu ve » hieu va, hieu van
x hoi » xa hoi, o hoi, x ho
di su » doi su, ki su, da su
ve am » va am

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) or (sach y)) nang x hoi. hieu ve am thuc ((dang hanh) OR (dang thanh)) di su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sach y)) nang x hoi. hieu ve am thuc ((dang hanh) OR (dang thanh)) di su triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) or (sach y)) nang x hoi. hieu ve am thuc ((dang hanh) OR (dang thanh)) di su triet*".