Perhaps you should try some spelling variations:
luan phan » luan van, luan hoan
hieu luan » hieu luat, hieu quan, tieu luan
su triet » su viet, su tien, ve triet
phan duc » pham duc, phan tu, phan dau
sach ky » sach y, sach ty, sach kem
va hanh » van hanh, va thanh, va danh
mang xa » lang xa, mang may, dang xay
nang ma » tang ma, sang ma, nang cao
sac ky » cac ky, sai ky
vi su » va su, ve su, ki su

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sach ky) OR (sac ky)) ((mang xa) or (nang ma)) hoi. hieu luan phan duc va hanh vi su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sac ky)) ((mang xa) OR (nang ma)) hoi. hieu luan phan duc va hanh vi su triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) OR (sac ky)) ((mang xa) or (nang ma)) hoi. hieu luan phan duc va hanh vi su triet*".