My new Tree book is coming out in July, but they're taking pre-orders at Amazon
https://www.amazon.co.uk/Trees-Black-White-Visual-Tour/dp/1682033503/ref=sr_1_1_twi_pap_1?ie=UTF8&qid=1518651702&sr=8-1&keywords=tony+howell+trees
And for my American and International friends: -
https://www.amazon.com/Trees-Black-White-Visual-Tour/dp/1682033503/ref=sr_1_2_twi_pap_1?s=books&ie=UTF8&qid=1518651629&sr=1-2&keywords=tony+howell+trees