Text Classification -- PCGAN-CHAR: Progressively Trained Classifier Generative Adversarial Networks for Classification of Noisy Handwritten Bangla Characters -- Weakly-Supervised Neural Categorization of Wikipedia articles -- Supervised Classifiers to Identify Hate Speech on English and Spanish Tweets -- Altmetrics -- An Overview of Altmetrics Research: A Typology Approach -- User Motivation Classification and Comparison of Tweets Mentioning Research Articles in the fields of Medicine, Chemistry and Environmental Science -- Understanding the Twitter Usage of Science Citation Index (SCI) Journals -- Scholarly Data Analysis and Recommendation -- Research Paper Recommender System with Serendipity using Tweets vs. Diversification -- The rise and rise of interdisciplinary research: Understanding the interaction dynamics of three major fields - Physics, Mathematics & Computer Science -- The Evolving Ecosystem of Predatory Journals: A Case Study in Indian Perspective -- Metadata and Entities -- Identifying and Linking Entities of Multimedia Franchise on Manga, Anime and Video Game from Wikipedia -- Impact of OCR Quality on Named Entity Linking -- Authoring Formats and Their Extensibility for Application Profiles -- Digital Libraries and Digital Archives Management -- Connecting Data for Digital Libraries: The Library, the Dictionary and the Corpus -- Modernisation of a 12 years old Digital Archive: Experiences and Lessons Learned -- Investigating the feasibility of digital repositories in private clouds -- Multimedia Processing -- Towards Automatic Cataloging of Image and Textual Collections with Wikipedia -- Automatic Semantic Segmentation and Annotation of MOOC Lecture Videos -- Play, Pause, and Skip: touch screen media player interaction on the move -- Search Engines -- Towards A Story Based Search Engine for Arabic Speaking Children -- Metadata-based Automatic Query Suggestion in Digital Library using Pattern Mining -- Investigating the effectiveness of client-side search/browse without a network connection -- SchenQL: A Concept of a Domain-Specific Query Language on Bibliographic Metadata -- Information Extraction -- Formalising Document Structure and Automatically Recognising Document Elements: A Case Study on Automobile Repair Manuals -- Weakly-Supervised Relation Extraction in Legal Knowledge Bases -- Social Media Aware Virtual Editions for the Book of Disquiet -- Language identification for South African Bantu languages Using Rank Order Statistics -- Posters -- Creating a Security Methods Taxonomy for Information Resource Management -- A Dynamic Microtask Approach to Collecting and Organizing Citizens' Opinions -- Sentiment Analysis of Tweets Mentioning Research Articles in Medicine and Psychiatry Disciplines -- Measurement and Visualization of IIIF Image Usages -- Improving OCR for Historical Documents by Modeling Image Distortion.

This book constitutes the refereed proceedings of the 21st International Conference on Asia-Pacific Digital Libraries, ICADL 2019, held in Kuala Lumpur, Malaysia, in November 2019. The 13 full, 13 short, and 5 poster papers presented in this volume were carefully reviewed and selected from 54 submissions. The papers were organized in topical sections named: text classification; altmetrics; scholarly data analysis and recommendation; metadata and entities; digital libraries and digital archives management; multimedia processing; search engines; information extraction; and posters.