Perhaps you should try some spelling variations:
thien van » thi van
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam thu
hanh tai » thanh tai, hang tai, han tai
ky dang » ky nang
ky danh » ky anh
va hanh » van hanh, va thanh, va danh
tai cua » thai cua, tai cuc, tri cua
nam tu » nam thu
cua te » cua 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 dang) OR (ky danh)) xa hoi. thien van ((nam thuc) or (nam tu)) va hanh tai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((ky dang) OR (ky danh)) xa hoi. thien van ((nam thuc) OR (nam tu)) va hanh tai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((ky dang) OR (ky danh)) xa hoi. thien van ((nam thuc) or (nam tu)) va hanh tai cua te".
• Adding a wildcard symbol may retrieve word variants: toc sach ((ky dang) OR (ky danh)) xa hoi. thien van ((nam thuc) or (nam tu)) va hanh tai cua te*.