Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
va triet » va thiet, va trien, ve triet
sach thi » sach tai, sach thieu, sach tham
sach thu » sach thue, sach thieu, sach tham
hieu va » lieu va, hieu qua
va tham » van tham, va cham, va thanh
thuc va » thuc vat, thuc dan, thuc day
han tai » hang tai, nhan tai, van tai
va han » va phan, van han, va hanh
tai va » thai va, mai va, tri va

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach thi) OR (sach thu)) hang ((cau hoi) or (xa hoi)). hieu va tham thuc va han tai va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach thi) OR (sach thu)) hang ((cau hoi) OR (xa hoi)). hieu va tham thuc va han tai va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach thi) OR (sach thu)) hang ((cau hoi) or (xa hoi)). hieu va tham thuc va han tai va triet".
• Adding a wildcard symbol may retrieve word variants: su ((sach thi) OR (sach thu)) hang ((cau hoi) or (xa hoi)). hieu va tham thuc va han tai va triet*.