Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
cam luc » cam xuc, cau luc
va hanh » van hanh, va thanh, va danh
hanh di » hanh vi, hanh de, hang di
cua tre » cua te, cuu tre, cua triet
v nang » va nang, vu nang, van nang
va cam » va cham, va cac, va cao
luc va » duc va, tuc va, loc va
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)) v nang xa hoi. hieu va cam luc va hanh di cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (doc sach)) v nang xa hoi. hieu va cam luc va hanh di cua tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) OR (doc sach)) v nang xa hoi. hieu va cam luc va hanh di cua tre*.