Prabhupada Letters :: 1968.

"My books are the ultimate source of knowledge. If you simply reproduce what I have explained surely you will come out victorious, even in the midst of so many great scholars."

Prabhupada Letters :: 1969.

"I am very glad to learn you have lectured nicely. Kirtana means whatever we hear from the Spiritual Master we repeat it again nicely. One who can reproduce the sound vibration heard from the Spiritual Master, he will be a good preacher."