Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
danh lai » danh sai, gianh lai, dinh lam
chat tuc » chat xuc, luat tuc, chat huu
hieu van » thien van, lieu va, hieu ve
lai cua » dai cua, hai cua, lai chau
va danh » va dinh, va dan, va hanh
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
tuc va » thuc va, truc va, tuc xa

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) or (hoc sach)) ky lang xa hoi. ((hieu van) OR (hieu va)) chat tuc va danh lai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sach)) ky lang xa hoi. ((hieu van) OR (hieu va)) chat tuc va danh lai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (hoc sach)) ky lang xa hoi. ((hieu van) OR (hieu va)) chat tuc va danh lai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (hoc sach)) ky lang xa hoi. ((hieu van) OR (hieu va)) chat tuc va danh lai cua tre*.