Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hanh tai » thanh tai, hang tai, han tai
vu sach » vu bach, su sach, vu khach
nang xa » nang x, lang xa, nang ma
qua cac » cua cac
cac duc » cac du, cao duc, cac dac
va hanh » van hanh, va thanh, va danh
tai cua » thai cua, tai cuc, tri cua
cua tre » cua te, cuu tre, cua triet

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((((vu sach) or (te sach))) or (toc sach)) ky nang xa hoi. hieu qua cac duc va hanh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((((vu sach) OR (te sach))) OR (toc sach)) ky nang xa hoi. hieu qua cac duc va hanh tai cua tre.
• Adding a wildcard symbol may retrieve word variants: ((((vu sach) or (te sach))) or (toc sach)) ky nang xa hoi. hieu qua cac duc va hanh tai cua tre*.