Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
dau cua » dai cua, day cua, cau cua
van dau » van dao, phan dau
thuc ca » thuc cua, thuc can, thuc cao
cua tre » cua te, cuu tre, cua triet
thi van » thi lan, thi hanh, thi nang
sach ky » sac ky, sach ty, sach kem
nang xa » nang x, lang xa, nang ma
ca van » cac van, cao van, can van

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((sach ky) OR (sach y)) nang xa hoi. ((thien van) or (thi van)) tham thuc ca van dau cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((sach ky) OR (sach y)) nang xa hoi. ((thien van) OR (thi van)) tham thuc ca van dau cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((sach ky) OR (sach y)) nang xa hoi. ((thien van) or (thi van)) tham thuc ca van dau cua tre".
• Adding a wildcard symbol may retrieve word variants: hoc ((sach ky) OR (sach y)) nang xa hoi. ((thien van) or (thi van)) tham thuc ca van dau cua tre*.