Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
cam duc » cam xuc, cao duc, nam duoc
hieu ve » hieu va, hieu van
nang ma » tang ma, sang ma, nang cao
sach va » sach xa, sach ha, sach dao
su viet » so viet
ma hoi » mai hoi, xa hoi, ma hoa
sach v » sach y, sach 2, sach vay
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 v) or (sach va)) nang ma hoi. hieu ve ((cam duc) OR (pham duc)) van hanh vi su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach v) OR (sach va)) nang ma hoi. hieu ve ((cam duc) OR (pham duc)) van hanh vi su viet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach v) or (sach va)) nang ma hoi. hieu ve ((cam duc) OR (pham duc)) van hanh vi su viet*".