Perhaps you should try some spelling variations:
day thanh » dat thanh, da thanh, dam thanh
dao thanh » ban thanh, tro thanh, de thanh
nam thuc » nam thuoc, am thuc, nam thu
cuu tre » cua tre, cau tren, cau treo
sach ky » sach y, sach ty, sach kem
hieu va » lieu va, hieu qua
nang o » nang co, nang ho, nang ro
sac ky » cac ky, sai ky
di cuu » di cau, di cua, dinh cuu
va nam » van nam, ha nam, va nay
o hoc » co hoc, mo hoc, so hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu ((sach ky) OR (sac ky)) nang o hoc. hieu va nam thuc ((dao thanh) or (day thanh)) di cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu ((sach ky) OR (sac ky)) nang o hoc. hieu va nam thuc ((dao thanh) OR (day thanh)) di cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu ((sach ky) OR (sac ky)) nang o hoc. hieu va nam thuc ((dao thanh) or (day thanh)) di cuu tre".
• Adding a wildcard symbol may retrieve word variants: vu ((sach ky) OR (sac ky)) nang o hoc. hieu va nam thuc ((dao thanh) or (day thanh)) di cuu tre*.