Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
khoa hoc » hoa hoc
va danh » va dinh, va dan, va hanh
hieu va » lieu va, hieu qua
ty hang » ly hang, ty xang, thi hang
ty dang » ty xang, ky dang, ty dong
cuu tre » cua tre, cau tren, cau treo
va cam » va cham, va cac, va cao
vi cuu » vi luu, vinh cuu

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 dang) or (ty hang)) khoa hoc. hieu va cam xuc ((van hanh) or (va danh)) vi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((ty dang) OR (ty hang)) khoa hoc. hieu va cam xuc ((van hanh) OR (va danh)) vi cuu tre.
• Adding a wildcard symbol may retrieve word variants: toc sach ((ty dang) or (ty hang)) khoa hoc. hieu va cam xuc ((van hanh) or (va danh)) vi cuu tre*.