Product and customer discovery for startups

Need a well written original article on "Product and customer discovery for startups" Example 1: http://www.marsdd.com/mars-library/blanks-customer-discovery-method-part-3-the-customer-development-model-in-value-proposition/ Example 2: http://market-by-numbers.com/customer-development/ Example 3: http://practicetrumpstheory.com/customer-development-checklist-for-my-web-startup-part-1/