Perhaps you should try some spelling variations:
sach ky » sach y, sach ty, sach kem
nang xa » nang x, lang xa, nang ma
hieu ve » hieu va, hieu van
va hanh » van hanh, va thanh, va danh
sac ky » cac ky, sai ky
ve cac » va cac, vien cac
cac bo » bac bo, cac co
bo va » bao va, do va, so va

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu ((sach ky) OR (sac ky)) nang xa hoi. hieu ve cac bo va hanh ((tai cuc) or (dai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ky) OR (sac ky)) nang xa hoi. hieu ve cac bo va hanh ((tai cuc) OR (dai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu ((sach ky) OR (sac ky)) nang xa hoi. hieu ve cac bo va hanh ((tai cuc) or (dai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: thu ((sach ky) OR (sac ky)) nang xa hoi. hieu ve cac bo va hanh ((tai cuc) or (dai cua)) tre*.