Credits and sources

• Textbooks: NCERT (Class 9 to 12) and NIOS Senior Secondary. The chapters here are rewritten from them for personal study; the original PDFs open from every chapter.
• English words: Master Stroke, the 10,000-headword dictionary made by the owner of this site.
• Fonts: Atkinson Hyperlegible Next and Mono by the Braille Institute (SIL Open Font License).
• Maths: KaTeX (MIT licence) draws the maths made when the site is built.
• Code: Astro and Preact (MIT), GSAP (GreenSock standard licence, free), ts-fsrs for spaced review (MIT), idb-keyval (Apache 2.0), Firebase (Google) for sign-in and sync.
• Word frequency: wordfreq by Robyn Speer (code MIT, data CC BY-SA 4.0), used to order words inside each band.
• Glossary sources: OpenStax textbooks (Rice University, CC BY 4.0), Wikidata (CC0) and the Australian Curriculum (ACARA, CC BY 4.0) were checked for each term's wording; the explanations are our own.
• Word themes: Princeton WordNet 3.0 (WordNet licence, free to use with this credit), read through NLTK (Apache 2.0), sorts the headwords into themes.
• Sentences: the English sentences in Sentence Builder come from Tatoeba (tatoeba.org, CC BY 2.0 FR); each card names its author, and all the authors are listed here.
• Proverbs: traditional English sayings, starting from Master Stroke's list and the sentences Tatoeba tags as proverbs; every meaning and example is our own.
• Every formula is checked with SymPy (BSD licence) before it appears.