Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
ty hang » ly hang, ty xang, thi hang
hang xa » hoang xa, hang va, hang ca
hieu va » lieu va, hieu qua
cao thu » cao thi, cac thu, ca thu
hanh di » hanh de, hang di, danh di
va cao » va cac, va co, va dao
thu va » thuc va, thue va, tu va
cua te » cua tu

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)) ty hang xa hoi. hieu va cao thu va ((hanh di) OR (hanh vi)) cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sach)) ty hang xa hoi. hieu va cao thu va ((hanh di) OR (hanh vi)) cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (hoc sach)) ty hang xa hoi. hieu va cao thu va ((hanh di) OR (hanh vi)) cua te".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (hoc sach)) ty hang xa hoi. hieu va cao thu va ((hanh di) OR (hanh vi)) cua te*.