Perhaps you should try some spelling variations:
hieu luan » hieu luat, hieu quan, tieu luan
luan phan » luan van, luan hoan
van hanh » van thanh, ban hanh, van anh
phan duc » pham duc, phan tu, phan dau
tu sach » thu sach, su sach, te sach
duc van » duc va, duc tan, duc manh
sach ty » sach y, sach tu, sach thu
nang ma » tang ma, sang ma, mang may
nang xa » nang x, lang xa, mang xa
su viet » so viet
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 ty ((nang xa) or (((nang ma) OR (nang cao)))) hoi. hieu luan phan duc van hanh vi su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((nang xa) OR (((nang ma) OR (nang cao)))) hoi. hieu luan phan duc van hanh vi su viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((nang xa) or (((nang ma) OR (nang cao)))) hoi. hieu luan phan duc van hanh vi su viet".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((nang xa) or (((nang ma) OR (nang cao)))) hoi. hieu luan phan duc van hanh vi su viet*.