Perhaps you should try some spelling variations:
"toc sach pham tai" » "toc sach tham tai", "toc sach phat tai", "toc sach phap tai", "hoc sach pham tai", "doc sach pham tai", "thuoc sach pham tai", "toc sach pham thi"
"toc sach pham van" » "toc sach tham van", "toc sach phat van", "toc sach phap van", "hoc sach pham van", "doc sach pham van", "thuoc sach pham van"
"tu sach thieu tri" » "tu sach thieu tai", "tu sach dieu tri", "tu sach thieu nhi", "thu sach thieu tri", "su sach thieu tri", "te sach thieu tri"

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 sach pham tai") OR ("toc sach pham van"))) or ("tu sach thieu tri"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("toc sach pham tai") OR ("toc sach pham van"))) OR ("tu sach thieu tri")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"toc sach pham tai\") OR (\"toc sach pham van\"))) or (\"tu sach thieu tri\"))".
• Removing quotes may allow a broader search: (((( toc sach pham tai ) OR ( toc sach pham van ))) or ( tu sach thieu tri )).
• Adding a wildcard symbol may retrieve word variants: (((("toc sach pham tai") OR ("toc sach pham van"))) or ("tu sach thieu tri"))*.