"... that the doctrine of The Christ is the 144,000 + 1"
Are there any references for this statement?
Yes pirata, plenty. Here's a sample:
From the Millions book (1920),
The word Christ here means anointed one. The word Messiah means the same thing. The Christ consists of Jesus glorified, the head, and the members of his body, which constitutes the church. "For as many of you as have been baptized into Christ have put on Christ. And if ye be Christ's, then are ye Abraham's seed, and heirs according to the promise." - p. 76.
Messiah's kingdom once established, Jesus and his glorified church constituting the great Messiah, shall minister the blessings to the people they have so long desired and hoped for and prayed might come. - p. 88.
From the Harp of God book (1921, 1928 ed.),
The word "Christ" signifies anointed. ... The Christ is the instrument or channel for the blessing of mankind. The Christ is composed of Jesus, the great and mighty head, and 144,000 members. (Revelation 7:4) Christ Jesus is the head and the church his body. - p. 191.
"The mystery" is the Christ, the anointed class, Jesus the head and his body members, designated in the Scriptures as 'the seed of Abraham, according to the promise'. (Colossians 1: 26, 27) It is the repeatedly announced purpose of Jehovah that through this seed all families of the earth shall be blessed. (Galatians 3: 8,16,27, 29) - p. 329.
To add: If you can access Gruss' book on The Four Presidents of the Watchtower Society on Google Books, and tap in the search box "the Christ," you'll see a few more examples.