gas.gs

var sheetId = "Your_sheet_id";
var sheetName = "Forrm_tab_name";

var schema = {
  timeStamp: 0,
  title: 3,
  authors: 2,
  isRead: 1,
  sourceShort: 4,
  year: 5,
  paperLink: 6,
  keywords: 8,
  note: 7,
  paperType: 10,
  issueLink: 11,
  source: 12,
};


function toDict (row) {
  var item = {}
  for (var key in schema) item[key] = row[schema[key]];
  return item;
};


function fetchPapers() {
  var paperListSpreadSheet = SpreadsheetApp
    .openById(sheetId)
    .getSheetByName(sheetName);
  
  var paperList = paperListSpreadSheet.getDataRange().getValues().map(function(row, index) {
    if (index == 0) return;  // header
    return toDict(row);
  }).filter(function(ret) { return ret != null} );
  
  Logger.log(paperList);
  return JSON.stringify(paperList);
}


function doGet() {
  const paperListJson = fetchPapers();
  return ContentService.createTextOutput(paperListJson);
}