Khan, Khalid Mohammed; Rahat, Shagufta; Choudhary, Muhammad Iqbal; Atta-ur-Rahman; Ghani, Usman; Perveen, Shahnaz; Khatoon, Shagufta; Dar, Ahsana; Malik, Abdul Helvetica Chimica Acta, 2002 , vol. 85, # 2 p. 559 - 570