Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
cam truc » cau truc, nam truc, lam truoc
va thanh » gia thanh, ban thanh, va tinh
va hanh » van hanh, va danh, ban hanh
hieu ve » hieu va, hieu van
sach ky » sac ky, sach y, sach ty
ve cam » ve cham, ve cac, va cam
va cap » va dap, va cao, va cai
di cua » dai cua, doi cua, de cua

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 ((va cap) OR (va cac)) phoi. hieu ve cam truc ((va hanh) or (va thanh)) di cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ky ((va cap) OR (va cac)) phoi. hieu ve cam truc ((va hanh) OR (va thanh)) di cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach ky ((va cap) OR (va cac)) phoi. hieu ve cam truc ((va hanh) or (va thanh)) di cua vat".
• Adding a wildcard symbol may retrieve word variants: doc sach ky ((va cap) OR (va cac)) phoi. hieu ve cam truc ((va hanh) or (va thanh)) di cua vat*.