Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
manh cua » doanh cua, ban cua
sang mai » sang ma, sang tai, lang mai
sach thu » sach thue, sach thieu, sach tham
mai hoi » mai khoi, dai hoi, lai hoi
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
duc van » duc tan, duc manh, duc phan
ve cam » ve cham, ve cac, va cam
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: su ((sach ky) or (sach thu)) sang mai hoi. hieu ve cam ((duc van) OR (duc va)) manh cua su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sach thu)) sang mai hoi. hieu ve cam ((duc van) OR (duc va)) manh cua su triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) or (sach thu)) sang mai hoi. hieu ve cam ((duc van) OR (duc va)) manh cua su triet*".