Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
cam thuc » am thuc, cam thu, can thuc
van hanh » van thanh, ban hanh, van anh
nam thuc » nam thuoc, am thuc, nam thu
hanh de » hanh ve, hanh kem
vu sach » vu bach, su sach, vu khach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
nang xa » lang xa, nang ma, mang xa
de su » den su, ve su, de tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ky ((nang xa) or (nang x)) hoi. hieu ve ((cam thuc) OR (nam thuc)) van hanh de su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky ((nang xa) OR (nang x)) hoi. hieu ve ((cam thuc) OR (nam thuc)) van hanh de su triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky ((nang xa) or (nang x)) hoi. hieu ve ((cam thuc) OR (nam thuc)) van hanh de su triet*".