Perhaps you should try some spelling variations:
cham thuc » nham thuc, pham thuc, tham thuc
nham thu » nham thuc, nam thu, pham thu
sach ky » sac ky, sach y, sach ty
te sach » toc sach
hieu ve » hieu va, hieu van
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
va dat » va dao, va dau, va dap
vi su » va su, ki su, oi su
ve su » va su

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ky lang xa hoi. hieu ve ((cham thuc) or (nham thu)) va dat ((vi su) OR (ve su)) hien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky lang xa hoi. hieu ve ((cham thuc) OR (nham thu)) va dat ((vi su) OR (ve su)) hien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky lang xa hoi. hieu ve ((cham thuc) or (nham thu)) va dat ((vi su) OR (ve su)) hien".
• Adding a wildcard symbol may retrieve word variants: te sach ky lang xa hoi. hieu ve ((cham thuc) or (nham thu)) va dat ((vi su) OR (ve su)) hien*.