Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
cham luc » cham soc, nhan luc, cham cuu
doc sach » hoc sach, nuoc sach, dac sac
van nang » van quang, van ban, van dong
va thanh » gia thanh, ban thanh, va tinh
va hanh » van hanh, va danh, ban hanh
va cham » va chat, va tham
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet
di cua » dai cua, doi cua, de 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) or (doc sach)) van nang xa hoi. hieu va cham luc ((va hanh) OR (va thanh)) di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) van nang xa hoi. hieu va cham luc ((va hanh) OR (va thanh)) di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (doc sach)) van nang xa hoi. hieu va cham luc ((va hanh) OR (va thanh)) di cua tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (doc sach)) van nang xa hoi. hieu va cham luc ((va hanh) OR (va thanh)) di cua tre*.