kali linux usblive

Hi all. The installation guide for kali usb is not the same in english and in spanish. Following the spanih guide remains in error.
http://es.docs.kali.org/installation...na-memoria-usb
http://docs.kali.org/installation/ka...ve-usb-install

in spanish: dd if=kali.iso of=/dev/sdb
in english: dd if=kali.iso of=/dev/sdb bs=512k

Adding persistence
in spanish: mkdir /mnt/usb
mount /dev/sdb2 /mnt/usb
echo "/ union" >> /mnt/usb/persistence.conf
umount /mnt/usb

in english: mkdir /mnt/usb
mount /dev/sdb2 /mnt/usb
echo "/ union" >> /mnt/usb/persistence.conf
umount /mnt/usb

only the english guide works. May be translation error.