Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
su triet » su viet, su tien, ve triet
hang doi » hang loi, huong doi, hang tai
vien cac » vien bach, vien dai, vien da
nang xa » nang x, lang xa, nang ma
sach xa » sach dao, sach nha, sach bai
cac tru » ca tru, cac tro, cac thu
tru van » truc van, tu van, tru va
hang di » hang vi, hang dien, hang dich
sach v » sach va, sach y, sach 2

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu ((sach v) or (sach xa)) nang xa hoi. hieu vien cac tru van ((hang di) OR (hang doi)) su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu ((sach v) OR (sach xa)) nang xa hoi. hieu vien cac tru van ((hang di) OR (hang doi)) su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu ((sach v) or (sach xa)) nang xa hoi. hieu vien cac tru van ((hang di) OR (hang doi)) su triet".
• Adding a wildcard symbol may retrieve word variants: vu ((sach v) or (sach xa)) nang xa hoi. hieu vien cac tru van ((hang di) OR (hang doi)) su triet*.