Perhaps you should try some spelling variations:
thien van » thi van
vat hanh » vat thanh, van hanh, va hanh
cau thuc » cau truc, cuu thuc, can thuc
thu sach » tu sach, thuat sach, thuoc sach
dang van » hoang van, hang va
cau tren » cu tren, dau tren, ca tren
sach ky » sac ky, sach y, sach ty
van cau » van dau, van hau, van chat
nang xa » nang x, lang xa, nang ma
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: thu sach ky ((nang xa) or (dang van)) hoi. thien van cau thuc vat hanh vi ((cua tre) or (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky ((nang xa) OR (dang van)) hoi. thien van cau thuc vat hanh vi ((cua tre) OR (cau tren)).
• Adding a wildcard symbol may retrieve word variants: thu sach ky ((nang xa) or (dang van)) hoi. thien van cau thuc vat hanh vi ((cua tre) or (cau tren))*.