Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
kho tang » cao tang
tang ma » mang may, tang van
van hac » van ha, van hai, van chat
van hoc » van hoa
duc van » duc va, duc tan, duc manh
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
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: ((toc sach) or (thuat sach)) kho tang ma hoi. hieu ((van hac) OR (van hoc)) duc van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (thuat sach)) kho tang ma hoi. hieu ((van hac) OR (van hoc)) duc van hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (thuat sach)) kho tang ma hoi. hieu ((van hac) OR (van hoc)) duc van hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (thuat sach)) kho tang ma hoi. hieu ((van hac) OR (van hoc)) duc van hanh vi cua tre*.