Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
sach ky » sac ky, sach y, sach ty
hanh va » hang va, hanh vi
loc van » luoc van, hoc van, loc va
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
lo van » le van, vo van, so van
ma hoi » mai hoi, xa hoi, me hoi
va cua » va chua, via cua, ca cua
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: thu sach ky nang ((ma hoi) or (ma hoa)). hieu ve cam ((loc van) OR (lo van)) hanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang ((ma hoi) OR (ma hoa)). hieu ve cam ((loc van) OR (lo van)) hanh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang ((ma hoi) or (ma hoa)). hieu ve cam ((loc van) OR (lo van)) hanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang ((ma hoi) or (ma hoa)). hieu ve cam ((loc van) OR (lo van)) hanh va cua tre*.