Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
duc van » duc va, duc tan, duc manh
sach ky » sac ky, sach y, sach ty
su viet » so viet
nang xa » lang xa, nang ma, mang xa
va cam » va cham, va cac, va cao
ve cam » ve cham, ve cac, ve cai
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: tu sach ky ((nang xa) or (nang x)) hoi. hieu ((ve cam) OR (va cam)) duc van hanh vi su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang xa) OR (nang x)) hoi. hieu ((ve cam) OR (va cam)) duc van hanh vi su viet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang xa) or (nang x)) hoi. hieu ((ve cam) OR (va cam)) duc van hanh vi su viet*".