Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cua viet » hoa viet, cua vat, cua dieu
cac tuc » cac tu, cac tac, cac nuoc
sach ky » sac ky, sach y, sach ty
cac toc » cac toi, cac nuoc, cac thoi
nang xa » nang x, lang xa, nang ma
hieu ve » hieu va, hieu van
ca viet » va viet, co viet, hoa viet
va dau » va dao
dau vi » dau ve, dau va, dat vi

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ky nang xa hoi. hieu ve ((cac tuc) or (cac toc)) va dau vi ((cua viet) or (ca viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky nang xa hoi. hieu ve ((cac tuc) OR (cac toc)) va dau vi ((cua viet) OR (ca viet)).
• Adding a wildcard symbol may retrieve word variants: toc sach ky nang xa hoi. hieu ve ((cac tuc) or (cac toc)) va dau vi ((cua viet) or (ca viet))*.