Schwinger's variational principle for

The file will be sent to you via the Telegram messenger. It may take up to 1-5 minutes before you receive it.

Note: Make sure you have linked your account to Z-Library Telegram bot.

The file will be sent to your Kindle account. It may take up to 1–5 minutes before you receive it.

Please note: you need to verify every book you want to send to your Kindle. Check your mailbox for the verification email from Amazon Kindle.