Perhaps you should try some spelling variations:
sach tham » sach nha
va trien » va truyen, va thiet, va tuyen
sach thu » sach thue, sach thieu, cach thuc
cham duc » cham soc, pham duy, phan duc
hieu van » hieu va, thien van, lieu va
va xanh » va danh, va hanh, va anh
xanh di » danh di, vanh dai, xanh tai
x hoi » xa hoi, o hoi, x ho
di va » dai va, di vao, doi va

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 thu) OR (sach tham)) nang x hoi. hieu van ((cham duc) or (pham duc)) va xanh di va trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach thu) OR (sach tham)) nang x hoi. hieu van ((cham duc) OR (pham duc)) va xanh di va trien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach thu) OR (sach tham)) nang x hoi. hieu van ((cham duc) or (pham duc)) va xanh di va trien".
• Adding a wildcard symbol may retrieve word variants: tu ((sach thu) OR (sach tham)) nang x hoi. hieu van ((cham duc) or (pham duc)) va xanh di va trien*.