Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
xa thanh » va thanh, ha thanh, ta thanh
ket van » viet van, ket doan, kien van
cam tuc » cam xuc, cam tu, nam thuc
hieu va » lieu va, hieu qua
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
va cam » va cham, va cac, va cao

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 lang xa hoi. hieu va cam tuc xa thanh ((ket va) or (ket van)) trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ky lang xa hoi. hieu va cam tuc xa thanh ((ket va) OR (ket van)) trien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ky lang xa hoi. hieu va cam tuc xa thanh ((ket va) or (ket van)) trien".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) ky lang xa hoi. hieu va cam tuc xa thanh ((ket va) or (ket van)) trien*.