Perhaps you should try some spelling variations:
vien cac » vien bach, vien dai, vien da
dien cuc » dien tu, dieu cua, dien hoc
cam thuc » am thuc, nam thuc, cam thu
so sach » so sanh, bo sach, co sach
va danh » va dinh, va dan, va hanh
nang xa » nang x, lang xa, nang ma
hieu ve » hieu van
hieu va » lieu va, hieu qua
thuc va » thuc vat, thuc dan, thuc day
sach 2 » sach y
2 nang » v nang

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach 2 nang xa hoi. ((hieu ve) or (hieu va)) cam thuc va danh ((dien cuc) OR (vien cac)) te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach 2 nang xa hoi. ((hieu ve) OR (hieu va)) cam thuc va danh ((dien cuc) OR (vien cac)) te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach 2 nang xa hoi. ((hieu ve) or (hieu va)) cam thuc va danh ((dien cuc) OR (vien cac)) te".
• Adding a wildcard symbol may retrieve word variants: so sach 2 nang xa hoi. ((hieu ve) or (hieu va)) cam thuc va danh ((dien cuc) OR (vien cac)) te*.