Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nhan luc » nang luc
van hanh » van thanh, ban hanh, van anh
duy sang » duy van, duy can, duy anh
hieu van » hieu va, thien van, lieu va
hanh de » hanh ve, hanh kem
cau luc » cau truc, cau phuc
mai hoi » mai khoi, dai hoi, lai hoi
cua tre » cua te, cuu tre, cua triet
y sang » _ sang
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: toc sach ((y sang) OR (duy sang)) mai hoi. hieu van ((cau luc) or (nhan luc)) van hanh de cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((y sang) OR (duy sang)) mai hoi. hieu van ((cau luc) OR (nhan luc)) van hanh de cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((y sang) OR (duy sang)) mai hoi. hieu van ((cau luc) or (nhan luc)) van hanh de cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ((y sang) OR (duy sang)) mai hoi. hieu van ((cau luc) or (nhan luc)) van hanh de cua tre*.