Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
thu sach » tu sach, thuat sach, thuoc sach
cac thoi » cac toi, cac tro, cac thu
tinh dai » trinh dai, tinh da, tinh hai
sach ty » sach y, sach tu, sach thu
ty lang » tay lang, ty xang, ty hang
lang xa » lang ha, dang xay, lang van
cac loc » cac lop, cac toc, cac hoc
cua su » qua su

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ty lang xa hoi. hieu vien ((cac loc) or (((cac thoi) OR (cac hop)))) may tinh dai cua su~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ty lang xa hoi. hieu vien ((cac loc) OR (((cac thoi) OR (cac hop)))) may tinh dai cua su.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ty lang xa hoi. hieu vien ((cac loc) or (((cac thoi) OR (cac hop)))) may tinh dai cua su".
• Adding a wildcard symbol may retrieve word variants: thu sach ty lang xa hoi. hieu vien ((cac loc) or (((cac thoi) OR (cac hop)))) may tinh dai cua su*.