Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
ty hang » ly hang, thi hang, thu hang
hieu va » lieu va, hieu qua
va hanh » van hanh, va thanh, va danh
co thu » co thua, cao thu, co thuc
thu va » thuc va, thue va, tu va
cua tu » cua tuc, cua su, cua cu
va co » vo co

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