Perhaps you should try some spelling variations:
thanh dat » thanh san, thanh hai, thanh van
thanh dai » thanh hai, thanh tai, thanh oai
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
nuoc van » nuoc va, nuoc san, luoc van
sach ky » sach y, sach ty, sach kem
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky

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 xa hoi. hieu va cac nuoc van ((thanh dai) OR (thanh dat)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sac ky)) nang xa hoi. hieu va cac nuoc van ((thanh dai) OR (thanh dat)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) or (sac ky)) nang xa hoi. hieu va cac nuoc van ((thanh dai) OR (thanh dat)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sac ky)) nang xa hoi. hieu va cac nuoc van ((thanh dai) OR (thanh dat)) cua tre*.