You can still avail of our discounted tickets for students.
This is a sentence from an English material I used in a lesson (https://eikaiwa.weblio.jp/information/travel-english/travel-english-buy-a-ticket-1). Is this usage of "avail" correct? I learnt at school that you say "you avail yourself of something". Does this sentence still make sense without "yourself"? Or is this just an error of the writer?