These resources are great for quick look-ups of concepts and definitions.
The Decision Maker's Handbook to Data Science, 2nd ed. by 
Statistical Applications for the Behavioral Sciences, 2nd ed. by 
Data Envelopment Analysis and Effective Performance Assessment by 
Introduction to Quantitative Data Analysis in the Behavioral and Social Sciences by 
Encyclopedia of Database Systems, 2nd ed. by
This multi-volume reference work serves as a gateway to information on all aspects of very large databases.
Practical Statistics for Data Scientists by
This practical guide explains how to apply various statistical methods to data science, tells you how to avoid their misuse, and gives you advice on what's important and what's not.... If you're familiar with the R programming language, and have some exposure to statistics, this quick reference bridges the gap in an accessible, readable format.
Introduction to the Mathematics of Finance by
The modern subject of mathematical finance has undergone considerable development, both in theory and practice, since the seminal work of Black and Scholes appeared a third of a century ago. This book is intended as an introduction to some elements of the theory that will enable students and researchers to go on to read more advanced texts and research papers.
Geisel also has the print edition. UC San Diego author.
The Oxford Handbook of Panel Data by
This handbook examines new developments in the theory and applications of panel data. It includes basic topics like non-stationary panels, co-integration in panels, multifactor panel models, panel unit roots, measurement error in panels, incidental parameters and dynamicpanels, spatial panels, nonparametric panel data, random coefficients, treatment effects, sample selection, count panel data, limited dependent variable panel models, unbalanced panel models with interactive effects and influential observations in panel data.
Items here provide theoretical background, point to models, and provide definitions.
Gartner has a lot of specialized content in its Research Library of interest to people in business analytics fields:
The Encyclopedia of Big Data by 
How to Read a Financial Report, 9th ed. by 
Spatial Analysis for the Social Sciences by Sample titles include:
Deep Learning in Time Series Analysis by 
Time Series for Data Science: Analysis & forecasting by 
Research practitioner's handbook on big data analytics by 
