Avoid random "free PDF download" websites. Many contain malware. Furthermore, pirating a foundational text undermines the publishing ecosystem that keeps classic works in print.
Igor Ansoff’s Corporate Strategy (1965) is widely recognized as the foundational text that established strategic management as a formal academic discipline. Originally titled corporate strategy igor ansoff pdf
: Creating and selling new products to the firm’s current customer base. Guide: Corporate Strategy — Igor Ansoff (PDF study