Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
nang co » nang cao, nang doc, nang noi
nang ra » nang ma, lang ra, nang ro
sach ky » sac ky, sach y, sach ty
va tuc » va thuc, va tu, va tac
vi cua » vai cua, di cua
ca tuc » cua tuc
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: thu sach ky ((nang co) or (nang ra)) hoi. hieu qua ((ca tuc) OR (va tuc)) van hanh vi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky ((nang co) OR (nang ra)) hoi. hieu qua ((ca tuc) OR (va tuc)) van hanh vi cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky ((nang co) or (nang ra)) hoi. hieu qua ((ca tuc) OR (va tuc)) van hanh vi cua te".
• Adding a wildcard symbol may retrieve word variants: thu sach ky ((nang co) or (nang ra)) hoi. hieu qua ((ca tuc) OR (va tuc)) van hanh vi cua te*.