Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
hieu van » hieu va, thien van, lieu va
hanh va » hang va, hanh vi
xuc van » duc van, luc van, xuc ban
van cam » van nam, van lam, van cau
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
su viet » so viet

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