Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
hieu van » hieu va, thien van, lieu va
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
khai cua » thai cua, hai cua, khan cua
sach ky » sac ky, sach y, sach ty
nang xa » lang xa, nang ma, mang xa
van cac » van hac, van cau, van bac
va dang » van dang, va nang, va lang
khi cua » chi cua, thai cua

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

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