Perhaps you should try some spelling variations:
nham thuc » nhan thuc, nam thuc, nham thu
vanh tai » van tai, hanh tai, anh tai
vanh dai » van dai, lanh dao, van dao
tu sach » thu sach, su sach, tu cach
thuc va » thuc vat, thuc dan, thuc day
va nham » va cham, va tham, va nha
hieu va » lieu va, hieu qua
dang xa » dang xay, lang xa, dang ha
ky dang » ky nang, ky danh
te sach » toc sach
cua tre » cua te, cuu tre, cua triet

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