Perhaps you should try some spelling variations:
cau triet » cau trieu, su triet, cua triet
dan hanh » dang hanh, dan khanh, dan thanh
thuc dan » thuc hanh, hoc dan, thuc vat
hanh di » hanh vi, hanh de, hang di
te sach » toc sach
vi dai » si dai, li dai, vien dai
ve cac » va cac, vien cac
_ lang » o lang, _ land
6 lang » o lang
di cau » da cau, diem cau

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

• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((6 lang) OR (_ lang)) xa hoi. hieu ((vi dai) OR (ve cac)) thuc dan hanh di cau triet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((6 lang) OR (_ lang)) xa hoi. hieu ((vi dai) or (ve cac)) thuc dan hanh di cau triet~".
• Adding a wildcard symbol may retrieve word variants: te sach ((6 lang) OR (_ lang)) xa hoi. hieu ((vi dai) or (ve cac)) thuc dan hanh di cau triet*.