Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
thuc dan » thuc hanh, hoc dan, thuc vat
dang xay » dang van, van xay
xay hoi » xa hoi, tay hoi, cay phoi
sach ky » sac ky, sach y, sach ty
thuc va » thuc vat, thuc day
ky dang » ky nang, ky danh
dan vai » dan va, dan tai, dan vat
vai cuu » vai cua
cuu tre » cua tre, cau tren, cau treo
va nam » ha nam, va nay

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