Perhaps you should try some spelling variations:
nuoc san » nuoc luan, nguoi san, nuoc quan
benh va » benh ve, benh dai, benh tai
xuc san » xuc ban, luc sang, thuc san
sach ky » sach y, sach ty, sach kem
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
nang o » nang co, nang ho, nang ro
sac ky » cac ky, sai ky
va cua » va chua, via cua, ca cua
va cam » va cham, va cac, va cao
o hoi » co hoi, o hoc, o hai

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sach ky) or (sac ky)) nang o hoi. hieu va cam ((xuc san) or (nuoc san)) benh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sac ky)) nang o hoi. hieu va cam ((xuc san) OR (nuoc san)) benh va cua tre.
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sac ky)) nang o hoi. hieu va cam ((xuc san) or (nuoc san)) benh va cua tre*.