Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
thuc dan » thuc hanh, hoc dan, thuc vat
sach ky » sac ky, sach y, sach ty
ky dang » ky nang, ky danh
van hoi » van hoc, van hoe, van loi
dan dao » van dao, dan dat, dan da
cuu tre » cua tre, cau tren, cau treo
dao va » dao van, tao va, do va
va cuu » va cau, va chu, va huu

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 ky dang ((van hoi) OR (van hoa)). hieu ((ha nam) or (van nam)) thuc dan dao va cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky dang ((van hoi) OR (van hoa)). hieu ((ha nam) OR (van nam)) thuc dan dao va cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky dang ((van hoi) OR (van hoa)). hieu ((ha nam) or (van nam)) thuc dan dao va cuu tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ky dang ((van hoi) OR (van hoa)). hieu ((ha nam) or (van nam)) thuc dan dao va cuu tre*.