Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, doanh tai
dan thanh » dang thanh, danh thanh, ban thanh
sach ky » sac ky, sach ty, sach kem
tai duc » tai cuc, mai duc, tai du
duc tre » duoc tren, duc tien
cao hoc » co hoc, cho hoc, chat hoc
ve cac » va cac, vien cac
ve cam » ve cham, va cam, ve cai

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 ky) or (sach y)) nang cao hoc. hieu ((ve cam) OR (ve cac)) cac dan thanh tai duc tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sach y)) nang cao hoc. hieu ((ve cam) OR (ve cac)) cac dan thanh tai duc tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) or (sach y)) nang cao hoc. hieu ((ve cam) OR (ve cac)) cac dan thanh tai duc tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sach y)) nang cao hoc. hieu ((ve cam) OR (ve cac)) cac dan thanh tai duc tre*.