Perhaps you should try some spelling variations:
nhan luc » nang luc
van hanh » van thanh, ban hanh, van anh
hieu van » hieu va, thien van, lieu va
hieu luc » hieu luat, hieu qua
te sach » toc sach
hanh de » hanh ve, hanh kem
cua tre » cua te, cuu tre, cua triet
cau luc » cau truc, cau phuc
sach 2 » sach y
2 nang » v nang
de cua » le cua, te cua, dieu 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 2 nang x ho. hieu van ((((hieu luc) or (cau luc))) or (nhan luc)) van hanh de cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach 2 nang x ho. hieu van ((((hieu luc) OR (cau luc))) OR (nhan luc)) van hanh de cua tre.
• Adding a wildcard symbol may retrieve word variants: te sach 2 nang x ho. hieu van ((((hieu luc) or (cau luc))) or (nhan luc)) van hanh de cua tre*.