Perhaps you should try some spelling variations:
thien van » thi van
nhan thuc » nhan luc, dan thuc, toan thuc
nha thuoc » nha nuoc, nha hoc
tu sach » thu sach, su sach, te sach
ma hanh » va hanh, da hanh, na hanh
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
cuu tre » cua tre, cau tren, cau treo
nang o » nang co, nang ho, nang ro
vi cuu » vi luu, vinh cuu
o hoi » co hoi, o hoc, o hai

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 nang o hoi. ((hieu va) or (thien van)) ((nha thuoc) OR (nhan thuc)) ma hanh vi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang o hoi. ((hieu va) OR (thien van)) ((nha thuoc) OR (nhan thuc)) ma hanh vi cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang o hoi. ((hieu va) or (thien van)) ((nha thuoc) OR (nhan thuc)) ma hanh vi cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang o hoi. ((hieu va) or (thien van)) ((nha thuoc) OR (nhan thuc)) ma hanh vi cuu tre*.