Perhaps you should try some spelling variations:
dai khoa » da khoa, dac khoa, dai hoa
hanh day » hanh may, han day, hanh dao
tai khoa » da khoa, noi khoa
bo sach » co sach, hoc sach
ve cham » va cham, ve chat, vu cham
day chu » day cho, cay chu, dao chu
va hanh » van hanh, va thanh, va danh
chu tre » cho tre, chu tri, cuu tre
sach ky » sac ky, sach y, sach ty
ky lang » ky nang, ky dang, ky tang
luc va » duc va, tuc va, loc va
ve cam » ve cac, va cam, ve cai

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

• Performing a fuzzy search may retrieve terms with similar spellings: bo sach ky lang ((dai khoa) or (tai khoa)). hieu ((ve cam) or (ve cham)) luc va hanh day chu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: bo sach ky lang ((dai khoa) OR (tai khoa)). hieu ((ve cam) OR (ve cham)) luc va hanh day chu tre.
• Adding a wildcard symbol may retrieve word variants: bo sach ky lang ((dai khoa) or (tai khoa)). hieu ((ve cam) or (ve cham)) luc va hanh day chu tre*.