Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
thu sach » thuat sach, thuoc sach, thu hoach
luu van » cuu van, luan van, luu hanh
luu ban » luu bang, luu dan, cuu ban
tu sach » su sach, te sach, tu cach
hieu vu » hieu va, hieu ve, hieu su
hang xa » hoang xa, hang va, hang ca
ty hang » ly hang, ty xang, thi hang
vu cham » va cham, vu kham, tu cham
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) or (thu sach)) ty hang xa hoi. hieu vu cham ((luu ban) OR (luu van)) hanh vi su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ty hang xa hoi. hieu vu cham ((luu ban) OR (luu van)) hanh vi su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thu sach)) ty hang xa hoi. hieu vu cham ((luu ban) OR (luu van)) hanh vi su triet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu sach)) ty hang xa hoi. hieu vu cham ((luu ban) OR (luu van)) hanh vi su triet*.