Perhaps you should try some spelling variations:
van khang » van thanh, van quang, van hanh
van khanh » van thanh, van hanh, van anh
toc sach » hoc sach, doc sach, thuoc sach
van nang » van quang, van ban, van dong
hieu ve » hieu va, hieu van
su viet » so viet
mai hoi » mai khoi, dai hoi, lai hoi
ve cam » ve cham, ve cac, va cam
v nang » va nang, vu nang, voi nang
ki su » ky su

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ((v nang) or (van nang)) mai hoi. hieu ve cam xuc ((van khang) OR (van khanh)) ki su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((v nang) OR (van nang)) mai hoi. hieu ve cam xuc ((van khang) OR (van khanh)) ki su viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((v nang) or (van nang)) mai hoi. hieu ve cam xuc ((van khang) OR (van khanh)) ki su viet".
• Adding a wildcard symbol may retrieve word variants: toc sach ((v nang) or (van nang)) mai hoi. hieu ve cam xuc ((van khang) OR (van khanh)) ki su viet*.