Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
kham duy » pham duy, khanh duy, pham duc
van hanh » van thanh, ban hanh, van anh
cua tre » cua te, cuu tre, dua tren
va hanh » va thanh, va danh, ban hanh
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
vu kham » vu khanh
hieu vu » hieu va, hieu ve, hieu su
hang ma » hang va, hang ca, tang ma
ty hang » ly hang, ty xang, thi hang
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: su sach ty hang ma hoi. hieu vu kham duy ((va hanh) or (van hanh)) lam ((cua tre) OR (cua triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty hang ma hoi. hieu vu kham duy ((va hanh) OR (van hanh)) lam ((cua tre) OR (cua triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty hang ma hoi. hieu vu kham duy ((va hanh) or (van hanh)) lam ((cua tre) OR (cua triet))".
• Adding a wildcard symbol may retrieve word variants: su sach ty hang ma hoi. hieu vu kham duy ((va hanh) or (van hanh)) lam ((cua tre) OR (cua triet))*.