Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
thien van » thi van
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
sach ky » sac ky, sach y, sach ty
van cac » van hac, van cau, van bac
va dang » van dang, va nang, va lang
thi cua » thai cua, tri cua, thi dua
thi cuc » tai cuc
x hoi » o hoi, x ho, 5 hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuoc sach ky nang ((x hoi) or (xa hoi)). thien van cac nuoc va dang ((thi cua) OR (thi cuc)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sach ky nang ((x hoi) OR (xa hoi)). thien van cac nuoc va dang ((thi cua) OR (thi cuc)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc sach ky nang ((x hoi) or (xa hoi)). thien van cac nuoc va dang ((thi cua) OR (thi cuc)) tre".
• Adding a wildcard symbol may retrieve word variants: thuoc sach ky nang ((x hoi) or (xa hoi)). thien van cac nuoc va dang ((thi cua) OR (thi cuc)) tre*.