While a quick Google search for "complex variables theory and applications kasana pdf free download" yields many results (such as archive.org, pdfdrive, or academia.edu uploads), users must be cautious:
Recommendation: If you find a PDF, ensure it is a legal preview or uploaded by the publisher. Respect intellectual property. However, for personal study/archiving of an out-of-print copy, the legal waters are gray; always default to purchasing a used physical copy (e.g., on Amazon or Abebooks).
The book’s treatment of integration along contours—especially when the contour deforms around singularities—is where Kasana excels. He visualizes the "indentation" technique for improper real integrals.
Simply downloading the PDF is not enough. You must study actively.