Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
nhan luc » nang luc
hieu van » hieu va, thien van, lieu va
hau luc » hau loc, cau luc, hieu luc
hanh le » thanh le, hanh ve, hanh de
cua tre » cua te, cuu tre, cua triet
nang xa » nang x, lang xa, nang ma
v nang » va nang, vu nang, van nang
le cua » ly cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) or (toc sach)) v nang xa hoi. hieu van ((hau luc) or (nhan luc)) van hanh le cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) v nang xa hoi. hieu van ((hau luc) OR (nhan luc)) van hanh le cua tre.
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (toc sach)) v nang xa hoi. hieu van ((hau luc) or (nhan luc)) van hanh le cua tre*.