Perhaps you should try some spelling variations:
lao dong » ha dong, van dong
so sach » so sanh, bo sach, co sach
ky dong » ly dong, ky dang, ky cong
hien tu » khien tu, dien tu
tu chat » tu phat, tu cham, du chat
xuc van » luc van, vuc van, xuc ban
duc van » duc va, duc tan, duc manh
cua tre » cua te, cuu tre, cua triet
va cua » va chua, via cua, ca cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ((ky dong) or (lao dong)) hoa hoc. hien tu chat ((xuc van) OR (duc van)) ban va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((ky dong) OR (lao dong)) hoa hoc. hien tu chat ((xuc van) OR (duc van)) ban va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ((ky dong) or (lao dong)) hoa hoc. hien tu chat ((xuc van) OR (duc van)) ban va cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach ((ky dong) or (lao dong)) hoa hoc. hien tu chat ((xuc van) OR (duc van)) ban va cua tre*.