{"work":{"id":"0358363a-ae9e-4317-b147-d5b895ad3b0c","openalex_id":null,"doi":"10.1007/978-3-662-12494-9","arxiv_id":null,"raw_key":null,"title":"Springer-Verlag, Berlin, 1999, pp","authors":null,"authors_text":"Grundlehren der mathematischen REFERENCES 91 Wissenschaften","year":1999,"venue":null,"abstract":null,"external_url":"https://doi.org/10.1007/978-3-662-12494-9","cited_by_count":null,"metadata_source":"doi_reference","metadata_fetched_at":"2026-06-29T09:13:15.447431+00:00","pith_arxiv_id":null,"created_at":"2026-05-09T00:04:27.896118+00:00","updated_at":"2026-06-29T09:13:15.447431+00:00","title_quality_ok":false,"display_title":"Metric spaces of non-positive curvatu re","render_title":"Metric spaces of non-positive curvatu re"},"hub":{"state":{"work_id":"0358363a-ae9e-4317-b147-d5b895ad3b0c","tier":"hub","tier_reason":"10+ Pith inbound or 1,000+ external citations","pith_inbound_count":18,"external_cited_by_count":null,"distinct_field_count":9,"first_pith_cited_at":"2019-06-30T10:57:01+00:00","last_pith_cited_at":"2026-06-17T21:18:47+00:00","author_build_status":"not_needed","summary_status":"needed","contexts_status":"needed","graph_status":"needed","ask_index_status":"not_needed","reader_status":"not_needed","recognition_status":"not_needed","updated_at":"2026-06-29T22:29:17.519441+00:00","tier_text":"hub"},"tier":"hub","role_counts":[{"context_role":"background","n":1},{"context_role":"method","n":1}],"polarity_counts":[{"context_polarity":"background","n":1},{"context_polarity":"use_method","n":1}],"runs":{},"summary":{},"graph":{},"authors":[]}}