Perhaps you should try some spelling variations:
sach thue » sach thieu, sach tham, cach thuc
sach thu » sach thieu, sach tham, cach thuc
cau tren » cu tren, dau tren, ca tren
bang xa » lang xa, bang va, mang xa
hieu ve » hieu va, hieu van
cac duc » cac du, cao duc, cac dac
va danh » va dinh, va dan, va hanh
danh vi » hanh vi, dinh vi, danh di
ve cac » va cac, vien cac

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 thu) or (sach thue)) bang xa hoi. hieu ve cac duc va danh vi ((cau tren) or (cua vat))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach thu) OR (sach thue)) bang xa hoi. hieu ve cac duc va danh vi ((cau tren) OR (cua vat)).
• Adding a wildcard symbol may retrieve word variants: tu ((sach thu) or (sach thue)) bang xa hoi. hieu ve cac duc va danh vi ((cau tren) or (cua vat))*.