必携
1
indispensable;essential;must-have
TOEICの学習に限らず、英語を学ぶのであれば英和辞典は必携の書の一つでしょう。
An English-Japanese dictionary is surely a must have book, not just for those taking TOEIC, but for all studying English.
2
handbook;manual;vade mecum
usu. in book titles