Perhaps you should try some spelling variations:
thien van » thi van
thuc dan » thuc hanh, hoc dan, thuc vat
te sach » toc sach
sach ky » sac ky, sach y, sach ty
dinh va » dinh van, dinh ve, tinh va
thuc va » thuc vat, thuc day
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
lang ha » long ha
ky lang » ky nang, ky dang, ky tang
ha hoi » hoa hoi, ha noi, xa hoi
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: te sach ky lang ha hoi. ((thien van) or (hieu va)) am ((thuc va) OR (thuc dan)) dinh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky lang ha hoi. ((thien van) OR (hieu va)) am ((thuc va) OR (thuc dan)) dinh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky lang ha hoi. ((thien van) or (hieu va)) am ((thuc va) OR (thuc dan)) dinh va cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ky lang ha hoi. ((thien van) or (hieu va)) am ((thuc va) OR (thuc dan)) dinh va cua tre*.