Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, doanh tai
hoc viet » hoc hien
hieu van » hieu va, thien van, lieu va
xa thanh » va thanh, ha thanh, ta thanh
co viet » so viet, o viet, hoa viet
sach ky » sac ky, sach ty, sach kem
van cam » van nam, van lam, van cau
cam te » cam tu, cam tien
x hoi » xa hoi, o hoi, x ho
te xa » te va

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

• Performing a fuzzy search may retrieve terms with similar spellings: so ((sach ky) OR (sach y)) nang x hoi. hieu van cam te xa thanh tai ((co viet) or (hoc viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so ((sach ky) OR (sach y)) nang x hoi. hieu van cam te xa thanh tai ((co viet) OR (hoc viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "so ((sach ky) OR (sach y)) nang x hoi. hieu van cam te xa thanh tai ((co viet) or (hoc viet))".
• Adding a wildcard symbol may retrieve word variants: so ((sach ky) OR (sach y)) nang x hoi. hieu van cam te xa thanh tai ((co viet) or (hoc viet))*.