Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
doc sach » hoc sach, toc sach, nuoc sach
sinh cua » manh cua, dinh cuu, sinh va
vinh cuu » dinh cuu, dinh cu, tinh cua
hieu van » hieu va, thien van, lieu va
sach ky » sac ky, sach y, sach ty
dang xa » dang xay, lang xa, dang ha
ky dang » ky nang, ky danh
doc va » duoc va, hoc va, loc va

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach ky dang xa hoi. hieu van thanh ((doc va) OR (duc va)) hanh ((vinh cuu) or (sinh cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ky dang xa hoi. hieu van thanh ((doc va) OR (duc va)) hanh ((vinh cuu) OR (sinh cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach ky dang xa hoi. hieu van thanh ((doc va) OR (duc va)) hanh ((vinh cuu) or (sinh cua)) tre".
• Adding a wildcard symbol may retrieve word variants: doc sach ky dang xa hoi. hieu van thanh ((doc va) OR (duc va)) hanh ((vinh cuu) or (sinh cua)) tre*.