Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
ky trong » ly trong, ke trong, cay trong
hieu van » hieu va, thien van, lieu va
va thanh » gia thanh, ban thanh, va tinh
thai cua » than cua, tai cuc, tri cua
van cau » van dau, van hau, van chat
va hanh » van hanh, va danh, ban hanh
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 trong) or (ky nang)) ma hoa. hieu van cau truc ((va hanh) OR (va thanh)) thai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((ky trong) OR (ky nang)) ma hoa. hieu van cau truc ((va hanh) OR (va thanh)) thai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((ky trong) or (ky nang)) ma hoa. hieu van cau truc ((va hanh) OR (va thanh)) thai cua te".
• Adding a wildcard symbol may retrieve word variants: toc sach ((ky trong) or (ky nang)) ma hoa. hieu van cau truc ((va hanh) OR (va thanh)) thai cua te*.