Dr Hang and Mr Wang have authored a Mathematical Olympiad book: Solving Problems in Geometry Insights and Strategies. It will be officially launched on 1 June 2017 at the Math Teachers' Conference at National Institute of Education. The book will be sold at a promotional price of S$25 (softcover) at the event.
This book is suitable for any reader with elementary geometrical knowledge at the lower secondary level. Each chapter includes sufficient scaffolding and is comprehensive enough for the purpose of self-study. Readers who complete the chapters on the basic theorems and techniques would acquire a good foundation in geometry and may attempt to solve many geometrical problems in various mathematical competitions. Meanwhile, experienced contestants in Mathematical Olympiad competitions will find a large collection of problems pitched at competitions at the international level, with opportunities to practise and sharpen their problem-solving skills in geometry.
You may also order the book online from here, at S$34 (softcover) with S$4 shipping.