Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
ban danh » ban doanh, ban hanh, ban dan
thuc ban » thuoc ban, thuc dan, thu ban
danh de » hanh de, dan de, dang de
va cham » va chat, va tham
su viet » so viet
ky dang » ky nang, ky danh
ky lang » ky nang, ky tang, tay lang
ve cam » ve cham, ve cac, va cam
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: toc sach ((ky lang) or (ky dang)) xa hoi. hieu ((ve cam) or (va cham)) thuc ban danh de su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((ky lang) OR (ky dang)) xa hoi. hieu ((ve cam) OR (va cham)) thuc ban danh de su viet.
• Adding a wildcard symbol may retrieve word variants: toc sach ((ky lang) or (ky dang)) xa hoi. hieu ((ve cam) or (va cham)) thuc ban danh de su viet*.