reference books is reference book's Plural Form

reference book

US 
UK 
  • n.参考书
  • Web参考书目;工具书;参考书籍
Plural Form:reference books  

Sample Sentence

Definition:
Category:AllAll,OralOral,WrittenWritten,TitleTitle,TechnicalTechnical
Source:AllAll,DictionaryDictionary,WebWeb
Difficulty:AllAll,EasyEasy,MiddleMiddle,HardHard