Perhaps you should try some spelling variations:
thien van » thi van
toc sach » hoc sach, doc sach, thuoc sach
thuc dan » thuc hanh, hoc dan, thuc vat
sach ky » sac ky, sach y, sach ty
thuc va » thuc vat, thuc day
van dam » van nam, van dao, van dau
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
va cuu » va chu, va huu
va cau » van cau, va cac, va dau

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