Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
lam thuc » lam thuoc, am thuc, nam thuc
sach ky » sac ky, sach y, sach ty
nang xa » lang xa, nang ma, mang xa
van lam » van nam
va chua » vua chua, ca chua, va chu
va cua » via cua, ca cua, ma cua
pham » phan

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

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