Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cua viet » ca viet, hoa viet, cua vat
nang xa » nang x, lang xa, nang ma
v nang » va nang, vu nang, van nang
tuc va » thuc va, truc va, tuc xa
va dan » ca dan, va dao, va dau
dan va » doan va, dan ca, ban va
va cua » va chua, via cua, ca cua

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