Perhaps you should try some spelling variations:
"hoc sach thuc nghiep so hoc" » "hoc sach thuc nghiem so hoc", "hoc sach thuat nghiep so hoc", "hoc sach thu nghiem so hoc", "hoc cach thuc nghiep so hoc", "hoc sach thu nghiep so hoc", "hoc sach thue nghiep so hoc", "hoc sach thuc nghiep nho hoc", "hoc sach thuc nghiep bao hoc", "hoc sach thuc nghiep va hoc", "hoc sinh thuc nghiep so hoc", "hoc cac thuc nghiep so hoc", "hoc anh thuc nghiep so hoc", "hoc sach thuc nghiep co hoc", "hoc sach thuc nghiep mo hoc", "hoc sach thuc nghiep so hoa"
"toc bach van nghiem y hoc" » "toc bach van nghe y hoc", "toc bach van nghia y hoc", "toc bach quang nghiem y hoc", "toc sach van nghiem y hoc", "truc bach van nghiem y hoc", "trac bach van nghiem y hoc", "toc bach dan nghiem y hoc", "toc cach van nghiem y hoc", "toc bach dang nghiem y hoc", "toc bach van nghiep y hoc", "toc bach van nghiem _ hoc", "toc bach van nghiem d hoc"

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("toc bach van nghiem y hoc") or ("hoc sach thuc nghiep so hoc"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("toc bach van nghiem y hoc") OR ("hoc sach thuc nghiep so hoc")).
• Removing quotes may allow a broader search: (( toc bach van nghiem y hoc ) or ( hoc sach thuc nghiep so hoc )).
• Adding a wildcard symbol may retrieve word variants: (("toc bach van nghiem y hoc") or ("hoc sach thuc nghiep so hoc"))*.