Perhaps you should try some spelling variations:
hang di » hang doi, hang vi, hang dien
hanh di » hanh vi, hanh de, danh di
sach ky » sach y, sach ty, sach kem
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
bo ban » co ban, lo ban, do ban
sac ky » cac ky, sai ky
va bac » van bac, va cac, va bai
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) or (sac ky)) nang x hoi. hieu va bac bo ban ((hanh di) OR (hang di)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sac ky)) nang x hoi. hieu va bac bo ban ((hanh di) OR (hang di)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) or (sac ky)) nang x hoi. hieu va bac bo ban ((hanh di) OR (hang di)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sac ky)) nang x hoi. hieu va bac bo ban ((hanh di) OR (hang di)) cua tre*.