Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
van nang » van quang, van ban, van dong
tu sach » su sach, te sach, tu cach
qua ban » cua ban, qua quan
duc ban » duc tan, duc van, dua ban
su viet » so viet
hieu ve » hieu va, hieu van
ve cac » va cac, vien cac
x hoi » xa hoi, o hoi, x ho
vi su » va su, ve su, ki 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) OR (thu sach)) van nang x hoi. hieu ve cac ((duc ban) OR (qua ban)) hanh vi su viet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (thu sach)) van nang x hoi. hieu ve cac ((duc ban) or (qua ban)) hanh vi su viet~".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (thu sach)) van nang x hoi. hieu ve cac ((duc ban) or (qua ban)) hanh vi su viet*.