Perhaps you should try some spelling variations:
van trinh » van thinh, van tinh, dan trinh
va trinh » va tinh, lap trinh, qua trinh
viet cua » viec cua, viet ca, viet qua
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
van lam » van nam
lam tuc » lam thuoc, lam truoc, luat tuc
sach ky » sac ky, sach y, sach ty
nang xa » lang xa, nang ma, mang xa
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 ky ((nang xa) or (nang x)) hoi. hieu van lam tuc ((va trinh) OR (van trinh)) viet cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang xa) OR (nang x)) hoi. hieu van lam tuc ((va trinh) OR (van trinh)) viet cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang xa) or (nang x)) hoi. hieu van lam tuc ((va trinh) OR (van trinh)) viet cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang xa) or (nang x)) hoi. hieu van lam tuc ((va trinh) OR (van trinh)) viet cua tre*.