Perhaps you should try some spelling variations:
sach thue » sach thieu, sach tham, cach thuc
sach thu » sach thieu, sach tham, cach thuc
trong ma » trong mau, trong ca, trong va
thuc va » thuc vat, thuc dan, thuc day
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
ve chat » va chat, van chat
ma hoi » mai hoi, xa hoi, ma hoa
tuc va » truc va, tuc xa, duc va
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach thue) or (sach thu)) trong ma hoi. hieu ve chat ((tuc va) OR (thuc va)) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach thue) OR (sach thu)) trong ma hoi. hieu ve chat ((tuc va) OR (thuc va)) hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach thue) or (sach thu)) trong ma hoi. hieu ve chat ((tuc va) OR (thuc va)) hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach thue) or (sach thu)) trong ma hoi. hieu ve chat ((tuc va) OR (thuc va)) hanh vi cua tre*.