Perhaps you should try some spelling variations:
tan thanh » tran thanh, tang thanh, toan thanh
hieu van » hieu va, thien van, lieu va
cua dieu » va dieu
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
van cac » van hac, van cau, van bac
cac duc » cac du, cao duc, cac dac
ca viet » va viet, co viet, hoa viet
x hoi » xa hoi, o hoi, x ho

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 ky nang x hoi. hieu van cac duc tan thanh san ((cua dieu) or (ca viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. hieu van cac duc tan thanh san ((cua dieu) OR (ca viet)).
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. hieu van cac duc tan thanh san ((cua dieu) or (ca viet))*.