Databases are a good for indepth research. They may contain articles in journals, papers in conference proceedings, newspapers, chapters in books, reports and reviews.
Relevant and specialised sources/databases
Scopus is a good starting point for finding articles on almost any topic. It is a multidisciplinary database covering the sciences, engineering, technology, medicine, social sciences, arts and humanities fields. Scopus contains millions of peer-reviewed journals, selected articles from trade journals, book chapters, edited volumes, reference works, conference papers and patents. It is also an excellent database for cited reference searching. Its contents are updated daily
Offers more than 1.7 million full-text dissertations in the humanities, social sciences, technology and more. Full-text available.
These are free and paid databases, maintained by either commercial outfits or by international agencies like the UN, WTO, World Bank etc,
Our World in Data (https://ourworldindata.org/https://ourworldindata.org/)
To aim of the site is to make available "Research and Data to make progress against the world's largest problems", and the main themes are Poverty, Disease, Hunger, Climate Change, War, Existential Risks and Inequality. The datasets are generally at regional, country and sometimes at city level, which makes it easier to do comparisons, but look out that you are using the same comparative years. Many of the datasets can be downloaded and re-used but do check if there are terms and conditions that apply for the dataset you want to use.
Singapore Statistics, aka SingStats (https://www.singstat.gov.sg/)
For statistics on most aspects of Singapore after 1992, this is your to-go site. Use the Singstats Table Builder feature to build the datasets you need as the data comes from over 60 government agencies, and part of the challenge is figuring out which agency does what. This is where you should consult a librarian at NUS Libraries, or your supervisor.