Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
nam truc » nam truoc, nam trung, nam thuoc
nam thuc » nam thuoc, am thuc, nam thu
dang xa » dang xay, lang xa, dang ha
sach ky » sac ky, sach y, sach ty
va hanh » van hanh, va thanh, va danh
ky dang » ky nang, ky danh
tai cua » thai cua, tai cuc, tri cua
va han » va phan, van han, va hang
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 dang xa hoi. hieu van ((nam truc) or (nam thuc)) ((va han) OR (va hanh)) tai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky dang xa hoi. hieu van ((nam truc) OR (nam thuc)) ((va han) OR (va hanh)) tai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky dang xa hoi. hieu van ((nam truc) or (nam thuc)) ((va han) OR (va hanh)) tai cua te".
• Adding a wildcard symbol may retrieve word variants: toc sach ky dang xa hoi. hieu van ((nam truc) or (nam thuc)) ((va han) OR (va hanh)) tai cua te*.