Perhaps you should try some spelling variations:
trinh vat » trinh van, trinh luat, sinh vat
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
va viet » hoa viet, san viet, mai viet
lang xa » lang ha, dang xay, lang van
ty lang » tay lang, ty xang, ty hang
va cam » va cham, va cac, va cai
luc va » duc va, tuc va
loc va » hoc va
vat va » dat va
va cao » va cac, va co, va dao

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 ty lang xa hoi. hieu ((va cam) OR (va cao)) ((luc va) or (loc va)) trinh vat va viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty lang xa hoi. hieu ((va cam) OR (va cao)) ((luc va) OR (loc va)) trinh vat va viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty lang xa hoi. hieu ((va cam) OR (va cao)) ((luc va) or (loc va)) trinh vat va viet".
• Adding a wildcard symbol may retrieve word variants: tu sach ty lang xa hoi. hieu ((va cam) OR (va cao)) ((luc va) or (loc va)) trinh vat va viet*.