Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nang xa » nang x, lang xa, nang ma
hieu ve » hieu va, hieu van
xuc van » luc van, xuc ban, thuc van
duc van » duc va, duc tan, duc manh
hanh va » hang va, hanh vi
su viet » so viet
ve cam » ve cham, ve cac, va cam

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 ve cam ((xuc van) OR (duc 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 hoi. hieu ve cam ((xuc van) OR (duc 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 hoi. hieu ve cam ((xuc van) OR (duc van)) hanh va su viet*".