Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
tru nang » tra nang, tri nang, truc nano
hanh vai » hanh vi, hanh va, hanh tai
vai cuu » vai cua
hieu va » lieu va, hieu qua
thuc va » thuc dan, thuc day
nang xa » nang x, lang xa, nang ma
cuu tre » cua tre, cau tren, cau treo

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) or (toc sach)) tru nang xa hoi. hieu va cac ((thuc va) OR (thuc vat)) hanh vai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) tru nang xa hoi. hieu va cac ((thuc va) OR (thuc vat)) hanh vai cuu tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (toc sach)) tru nang xa hoi. hieu va cac ((thuc va) OR (thuc vat)) hanh vai cuu tre*".