Perhaps you should try some spelling variations:
trinh vat » trinh van, trinh luat, sinh vat
hieu hien » bieu hien, dieu hien, chieu chien
hien cac » thien cac, vien cac, hieu cac
kinh va » kinh van, tinh va, sinh va
cac lao » ca lao, cac loai, cac giao
sach ky » sach y, sach ty, sach kem
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet
lao va » tao va, cao va, bao va
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 hien cac lao va ((kinh va) or (trinh vat)) 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 hien cac lao va ((kinh va) OR (trinh vat)) 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 hien cac lao va ((kinh va) or (trinh vat)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) OR (sac ky)) nang xa hoi. hieu hien cac lao va ((kinh va) or (trinh vat)) cua tre*.