H.P.V. Nunn's Short Syntax of New Testament Greek is a reference grammar for beginning and intermediate Greek students. It includes two appendices of Greek readings.
Nunn's Elements of New Testament Greek is a learning grammar, designed to be used as a first year Greek textbook, or for self-study. It consists of 37 lessons, each with introductions to grammatical concepts, vocabulary lists, and translation exercises (both Greek to English and English to Greek). The Elements book is keyed to the Syntax book to provide students with an avenue for further reference and study.
A Key to the Elements of New Testament Greek allows people using Nunn's books for self-study to check their work.
The Logos Bible Software Series X (Libronix) editions for these books are based on the 1923 editions. Together, these three books are an excellent introduction to reading the New Testament in Greek.