The Narrow Pathway to the Golden Gate by A T Schofield and published by Classics.
“My dear young friends, this book is specially written for the help of those of you who, having entered at the “straight gate” are walking in the “narrow way.” In our day God is blessing His word to the young in a very remarkable way; and it is from an earnest desire to help such that I have written pages, looking to God to use them for His own glory.
Before you read them, however, I have to make one request. I find it of the greatest value to be obliged to search God’s word for one’s self, and in order to induce you to do this. I have left all the chapter and verses referred to in this book for the reader to fill in for themselves, and I want you to promise that you will fill in each blank space as you go along for I feel that the Lord will bless you as you search His word. I have tried to be as simple and plain as possible even where the truth taught is rather difficult.”