Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
kien cau » khien cau, thien cau, ket cau
hien cau » khien cau, thien cau, hien cac
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
va cam » va cham, va cac, va cao
tuc va » thuc va, truc va, duc va

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ky nang xa hoi. hieu va cam ((tuc va) OR (tuc xa)) kinh ((kien cau) or (hien cau)) tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky nang xa hoi. hieu va cam ((tuc va) OR (tuc xa)) kinh ((kien cau) OR (hien cau)) tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky nang xa hoi. hieu va cam ((tuc va) OR (tuc xa)) kinh ((kien cau) or (hien cau)) tren".
• Adding a wildcard symbol may retrieve word variants: toc sach ky nang xa hoi. hieu va cam ((tuc va) OR (tuc xa)) kinh ((kien cau) or (hien cau)) tren*.