Perhaps you should try some spelling variations:
sach thuat » sach tham, dich thuat, sach phat
cac thuat » va thuat, hoc thuat, cac thu
hanh vai » hanh vi, hanh va, hanh tai
vai cua » dai cua, hai cua, lai cua
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet
va cam » va cham, va cac, va cao
luc va » tuc va, loc va

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 thuat) OR (cac thuat)) nang xa hoi. hieu va cam ((luc va) or (duc va)) hanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc ((sach thuat) OR (cac thuat)) nang xa hoi. hieu va cam ((luc va) OR (duc va)) hanh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc ((sach thuat) OR (cac thuat)) nang xa hoi. hieu va cam ((luc va) or (duc va)) hanh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: toc ((sach thuat) OR (cac thuat)) nang xa hoi. hieu va cam ((luc va) or (duc va)) hanh vai cua tre*.