Perhaps you should try some spelling variations:
cham thuc » nham thuc, pham thuc, tham thuc
nham thu » nham thuc, nam thu, pham thu
te sach » toc sach
su hien » su kien, thu hien, nhu hien
sach ky » sac ky, sach y, sach ty
su tien » su kien, tu tieng, dau tien
hieu ve » hieu va, hieu van
lang ha » long ha
ky lang » ky nang, ky dang, ky tang
ha hoi » hoa hoi, ha noi, xa hoi
va dat » va dao, va dau, va dap
dat ve » dat va, dat de, dat vi

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 ha hoi. hieu ve ((cham thuc) or (nham thu)) va dat ve ((su hien) or (su tien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky lang ha hoi. hieu ve ((cham thuc) OR (nham thu)) va dat ve ((su hien) OR (su tien)).
• Adding a wildcard symbol may retrieve word variants: te sach ky lang ha hoi. hieu ve ((cham thuc) or (nham thu)) va dat ve ((su hien) or (su tien))*.