Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
duc manh » suc manh, duc anh, duc minh
hanh dai » hanh tai, hanh dao, vanh dai
tu sach » su sach, te sach, tu cach
xang xa » lang xa, mang xa, ang xa
hieu ve » hieu va, hieu van
ve pham » vi pham, v pham, ve phan
duc van » duc va, duc tan, duc phan
cua te » cua tu

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 xang xa hoi. hieu ve pham ((duc van) OR (duc manh)) hanh dai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ty xang xa hoi. hieu ve pham ((duc van) OR (duc manh)) hanh dai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thu sach)) ty xang xa hoi. hieu ve pham ((duc van) OR (duc manh)) hanh dai cua te".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu sach)) ty xang xa hoi. hieu ve pham ((duc van) OR (duc manh)) hanh dai cua te*.