Perhaps you should try some spelling variations:
thien van » thi van
nam thuc » nam thuoc, am thuc, nam thu
te sach » toc sach
sach ky » sac ky, sach y, sach ty
thuc va » thuc vat, thuc dan, thuc day
hanh di » hanh vi, hang di, danh di
hanh de » hanh ve, hanh kem
ca tren » cau tren, cu tren, la tren

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

• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky nang x ho. ((lieu va) OR (thien van)) nam thuc va ((hanh di) OR (hanh de)) ca tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky nang x ho. ((lieu va) or (thien van)) nam thuc va ((hanh di) OR (hanh de)) ca tren~".
• Adding a wildcard symbol may retrieve word variants: te sach ky nang x ho. ((lieu va) or (thien van)) nam thuc va ((hanh di) OR (hanh de)) ca tren*.