Perhaps you should try some spelling variations:
dieu kien » dieu khien, dien bien
kinh va » kinh van, tinh va, sinh va
va kinh » va tinh, qua kinh
cac lao » cac loai, cac giao, cac lang
sach ky » sac ky, sach y, sach kem
sach ty » sach y, sach tu, sach thu
cua tre » cua te, cuu tre, cua triet
ca lao » cua lao, ca dao, ca cao
va cua » va chua, via cua, ca cua
x hoi » xa hoi, o hoi, x ho

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: tu ((sach ky) OR (sach ty)) nang x hoi. dieu kien ((cac lao) OR (ca lao)) va kinh va cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) OR (sach ty)) nang x hoi. dieu kien ((cac lao) or (ca lao)) va kinh va cua tre~".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) OR (sach ty)) nang x hoi. dieu kien ((cac lao) or (ca lao)) va kinh va cua tre*.