Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cau tren » cu tren, dau tren, ca tren
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
va tinh » may tinh
tinh va » tich va, trinh van, trinh vat
va cao » va cac, va co, va dao
cao tu » cao thu, co tu, cao su
va cau » van cau, va cac, va dau

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)) ky nang xa hoi. hieu va cao tu va tinh va cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ky nang xa hoi. hieu va cao tu va tinh va cau tren.
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (toc sach)) ky nang xa hoi. hieu va cao tu va tinh va cau tren*.