Perhaps you should try some spelling variations:
hac thuc » hoc thuc, ha thuc, thach thuc
va danh » va dinh, va dan, va hanh
thuc va » thuc vat, thuc dan, thuc day
sach ky » sac ky, sach ty, sach kem
hieu va » lieu va, hieu qua
nang o » nang co, nang ho, nang ro
vi cuu » vinh cuu
vi luu » vi lua
va hac » van hac, va khac, va cac
o hai » co hai, so hai, o lai

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuoc ((sach ky) OR (sach y)) nang o hai. hieu va hac thuc va danh ((vi cuu) or (vi luu)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc ((sach ky) OR (sach y)) nang o hai. hieu va hac thuc va danh ((vi cuu) OR (vi luu)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc ((sach ky) OR (sach y)) nang o hai. hieu va hac thuc va danh ((vi cuu) or (vi luu)) tre".
• Adding a wildcard symbol may retrieve word variants: thuoc ((sach ky) OR (sach y)) nang o hai. hieu va hac thuc va danh ((vi cuu) or (vi luu)) tre*.