Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
hanh ki » hanh vi, hanh ky, hanh kien
dua ban » dia ban, cua ban, qua ban
duc ban » duc tan, duc van, duc man
va cham » va chat, va tham
hieu va » lieu va, hieu qua
vu nang » vuc nang, va nang, vu dang
su viet » so viet
v nang » va nang, van nang, voi 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.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ((v nang) OR (vu nang)) x hoi. hieu va cham ((duc ban) or (dua ban)) hanh ki su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((v nang) OR (vu nang)) x hoi. hieu va cham ((duc ban) OR (dua ban)) hanh ki su viet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((v nang) OR (vu nang)) x hoi. hieu va cham ((duc ban) or (dua ban)) hanh ki su viet*".