Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
van hanh » van thanh, ban hanh, van anh
cam thuc » am thuc, nam thuc, can thuc
hieu van » hieu va, thien van, lieu va
sach vu » sach va, sach tu, sach uu
cam thu » nam thu, cac thu, ca thu
su sach » so sach, vu sach
dang x » dang y, dang _, dang h
vi su » va su, ve su, ki su

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

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