Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
hanh ki » hanh vi, hanh ky, hanh kien
dua ban » cua ban, qua ban, mua ban
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
duc ban » duc tan, duc van, duc man
ve cac » va cac, vien cac
sach v » sach va, sach y, sach 2
v nang » va nang, vu nang, van nang
x hoi » xa hoi, o hoi, x ho
ki su » ky su

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: tu sach v nang x hoi. hieu ve cac ((duc ban) OR (((dua ban) OR (dia ban)))) hanh ki su triet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach v nang x hoi. hieu ve cac ((duc ban) or (((dua ban) OR (dia ban)))) hanh ki su triet~".
• Adding a wildcard symbol may retrieve word variants: tu sach v nang x hoi. hieu ve cac ((duc ban) or (((dua ban) OR (dia ban)))) hanh ki su triet*.