Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, hieu ve
benh day » benh dai, benh cay, benh nay
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
nang xa » nang x, lang xa, nang ma
xuc ban » duc ban, cuc ban, quoc ban
benh da » benh dai, benh va, benh do
cua tre » cua te, cuu tre, cua triet

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

• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ty nang xa hoi. ((hieu van) OR (lieu va)) cam xuc ban ((benh day) OR (benh da)) cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ty nang xa hoi. ((hieu van) or (lieu va)) cam xuc ban ((benh day) OR (benh da)) cua tre~".
• Adding a wildcard symbol may retrieve word variants: thu sach ty nang xa hoi. ((hieu van) or (lieu va)) cam xuc ban ((benh day) OR (benh da)) cua tre*.