Perhaps you should try some spelling variations:
dang hai » dang khai, hang hai, dung hai
su triet » su viet, su tien, ve triet
co sach » bo sach, cuon sach, hoc sach
sach ty » sach y, sach tu, sach thu
hang ma » hang ca, tang ma, nang ma
hieu ve » hieu va, hieu van
ve pham » vi pham, v pham, ve phan
duc xa » duoc xa, tuc xa, duc ha
hai su » hai vu, lai su, hai so

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

• Performing a fuzzy search may retrieve terms with similar spellings: co sach ty ((hang ma) or (hang va)) hoi. hieu ve pham ((duc xa) OR (duc va)) dang hai su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: co sach ty ((hang ma) OR (hang va)) hoi. hieu ve pham ((duc xa) OR (duc va)) dang hai su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "co sach ty ((hang ma) or (hang va)) hoi. hieu ve pham ((duc xa) OR (duc va)) dang hai su triet".
• Adding a wildcard symbol may retrieve word variants: co sach ty ((hang ma) or (hang va)) hoi. hieu ve pham ((duc xa) OR (duc va)) dang hai su triet*.